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->''How hard can rocket science be, anyway?''

''Kerbal Space Program'' is a game about a [[LittleGreenMen green humanoid species]] known as the Kerbals as they start a space program. Superficially similar to ''VideoGame/{{Orbiter}}'', the difference between the two has been likened to the difference between making to-scale miniatures for architectural design and playing with [=LEGO=] bricks with rocket fuel in them, which you then hurl with glee at your sister.

The game offers three game modes to suit your style of play. The first is little more than a sandbox. You're set loose upon a space center complete with a vehicle assembly building and a launch pad, a bin full of rocket parts, ground personnel composed entirely of yes-men who build and wheel onto the launch pad anything you design no matter how crazy it is, and some astronauts to crew your creations. The second version is Science, in which you have to conduct experiments in order to unlock various piece parts, as you start off with just the very basics. The third mode is full blown Career mode, and you have to juggle a budget, job offers, your Kerbalnauts and conduct Science similar to the Science mode (which used to be the old Career mode, prior to 0.24). Essentially, you have to manage the entire Space Program. The number of parts has risen dramatically in recent releases, and the community is already cranking out fanmade addons at an impressive pace on top of that.

After four and a half years of development, version 1.0 was released on April 27th, 2015. This version, on top of taking the game out of Early Access, added the last gameplay mechanics that were left to implement: Aerodynamics, heating, fairings, resource mining and, last but not least, female kerbonauts. The game is still being developed, though, and is currently in version 1.2.

Its official website and download location is [[http://kerbalspaceprogram.com/ here]], and a trailer for the game can be found [[http://youtu.be/RkDOOsGg-9I here]]. Starting with 0.19, it's also available on UsefulNotes/{{Steam}}. It was ported to UsefulNotes/PlayStation4 and UsefulNotes/XboxOne in July 2016, and a UsefulNotes/WiiU version has been announced.

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!!This game contains examples of the following:

* AbortedArc: At one point, [[http://pastebin.com/3vvjushy there was a plan for a loose narrative connecting the Easter eggs.]] Then, Nova Silisko (the person who conceived it) left the team, and this story is most likely abandoned. He has stated on multiple occasions that he regrets sharing the so-called "plan" and generally wishes people would stop bringing it up.
* AcePilot: Pilot Kerbals can enhance the control of vessels, allowing them to point to particular vectors and enhancing their existing stability systems, getting that much more mobility out of craft. The more experienced they are, the better they get. Although, once you unlock the probe cores that can do everything a veteran pilot can, they become somewhat obsolete... as long as your probe core have power and is in range of the comm relays (1.2)
* AcceptableBreaksFromReality: Some minor ones involved in craft construction. Components requiring/generating power will be considered connected as long as there is some physical connection between them (even if there are no visible wires). To a lesser extent, the same is true of fuel(and it cases it isn't, fuel pipes just have to connect somewhere on both sides). Most noticeable are docking ports, that allow transfer of fuel, power and kerbals regardless of craft construction (Is there a giant fuel tank between a docked spacecraft and another living space? It doesn't matter. Kerbals can still move through it without problem). Even weirder if you use a mod like Kerbal attachment system, that allows you to detach/attach parts in flight.
** Life Support is not a factor, which simplifies rescues and mission planning somewhat. It can lead to some FridgeHorror if you choose to not rescue a kerbal stranded in deep space, [[AndIMustScream since they will never die and instead drift forever with nothing to do, no hope of returning home]], and [[ArsonMurderAndJaywalking no snacks]].
* AerithAndBob: Somewhat odd example - all the Kerbonauts have names that sound fairly Middle American, but anyone who is not an orange suit has a name randomly generated from a list of prefixes and suffixes. So alongside Jeb, Bill, and Bob may sit Melzer, Bardrin, or Billy-Bobfred.
** Although there are some characters who are named after historic space personages ("Buzz", for instance) or famous Kerbal Space Program Let's Players.
* AfterActionReport: Many players like to share accounts of their most recent or most memorable accomplishments. The [[http://forum.kerbalspaceprogram.com/forumdisplay.php/55-Mission-Reports Mission Reports]] section of the official forums is set up explicitly for this. People also like to assemble collections of screenshots into captioned Imgur albums and share them as brief {{Machinomics}}.
* AlienSea: Eve, whose oceans are purple and ([[WordOfGod according to the devs]]) literally {{Made of Explodium}}.
** The Outer Planets mod has Tekto, the Titan analogue. The oceans are green, and presumably made of hydrocarbons
** Laythe’s oceans seem pretty normal – until you realize they are liquid at a subzero temperature.
*** Looking at the chart on the wiki it seems that they are around 1.85 celsius.
* AlienSky: Eve again, with a thick, heavy purple sky. Laythe also counts; from some angles it looks a lot like you could be on Kerbin until you turn around and see a massive gas giant hanging in the sky.
* AllegedCar: Rovers are a bit... unstable at the moment, sometimes shaking themselves apart or exploding with little reason. The devs are [[http://forum.kerbalspaceprogram.com/content/345-KSP-and-Unity-5 working to correct this]] for version 1.1.
* AndIMustScream: Kerbals don't need food or water, meaning if a vehicle is stuck on the moon, orbiting somewhere or flying out into space, those Kerbals won't die and suffer a FateWorseThanDeath. [[TheWorldIsJustAwesome They don't seem to mind, though]].
** Various life support mods are used by players who do want them to die.
* ArbitraryHeadcountLimit: Until the VAB and SPH are upgraded, you are limited to a size restriction (to fit within the hangar) and a total parts number restriction. There's no weight to a parts value, meaning you may have to choose between a Mainsail rocket booster or a handheld thermometer, because putting both on would put you 1 part above the limit.
* ArtificialAtmosphericActions: In the VAB and SPH, mostly consisting of various personnel trying to look busy and important.
* ArtisticLicensePhysics: The game is generally pretty good about using real physics, but that makes the few places where it goes off of it stick out more. For example, a satellite is only calculated to be in one celestial body's sphere of influence at a time, making all exo-atmospheric orbits stable without Lagrange points. Reasons not to include such physics features include performance (calculating and predicting the effect of tens of celestial bodies on potentially hundreds of spacecraft would slow the game to a crawl), simplicity for players (it's much easier to see what's going on), and most importantly, orbital stability (the gravity of the Mun would cause standard Kerbin orbits to slowly destabilize over time, forcing players to make tedious stationkeeping maneuvers like real satellites have to do).
** Though Squad has actually written on their FAQ page to stop asking for Langrangian points to be implemented, much to the chagrin of several astronomy nerds (the L4 and L5 points are ideal places to put a long-term space-station).
* ArtStyleDissonance: Don't let the cartoonish proportions of the kerbonauts or their rockets fool you; the game is deceptively difficult if you don't already know a little bit about how actual rocketry works.
* AscendedGlitch: The Space Kraken. [[spoiler:A dead one can be found on Bop, one of Jool's moons.]]
* AscendedMeme: The loading screen roll references a few that are popular on the forums, such as "[[XtremeKoolLetterz Adding K to Every Word]]", and contract descriptions occasionally use the phrase [[OhMyGods "Kraken help you if..."]]
* AsteroidMiners: Asteroids can be used as a renewable fuel source if your craft is equipped with the proper harvesting and refining equipment.
* AsteroidThicket: {{Averted|Trope}}. While asteroids were added in the aptly-titled ''Asteroid Redirect Mission'' update, they are few and far between, and players have to go out of their way to detect them in the first place, let alone rendezvous with one, conduct experiments, or change its course.
* AwesomeButImpractical: There's nothing preventing you from making a rocket far larger than one you really need to complete the mission.
** The ion engine. The most fuel efficient engine in the game by far, but it's expensive, uses a lot of electricity, and has a very low thrust output (despite still being several times more powerful than real-life ion engines, especially due to a recent update that upped the thrust level appreciably). As a result, the burn time needed to get anywhere interesting can take ''hours'', and you can only accelerate time up to 4x when engines are on.
** The nuclear rocket isn’t much better, being huge in length, rather low on thrust, and merely twice as efficient as regular ones. On the upside, the 1.0 update made it not require oxidizer, meaning you can leave it out of your fuel tanks to save on mass.
** Using SSTO [[SpacePlane spaceplanes]] for, well, ''anything'' really. They're difficult to design, they're expensive to construct, and they don't really do anything that can't be done with a plain old rocket. Their only major advantage is that they're easier to re-use than conventional rockets, making them a bit cheaper in the long term.
** However, like most things in the game, all of the above can become DifficultButAwesome with the application of a little ingenuity.
** Save for Lithobr(e)aking, which is deliberately crashing just right on a suitable surface (read: the flats on Minmus). Sure it's pretty funny to see it happen when one gets it right, it also winds up destroying everything that hits the rock beneath before it loses any kinetic force it has left.
* {{Badass}}: Jebediah and Valentina Kerman, along with many other randomly generated Kerbals if they have a hidden "[=BadS=]" trait set to true. They always smile no matter what's happening and even if something explodes, they get worried for a few seconds before resuming their smiling. If either of them looks freaked out, you have done something horribly wrong.
** A possible coincidence: If you take the hex code [=#BADA55=] and turn it into a color, that color is close to the shade of Kerbal skin. (The actual color is [=#CBDB81=].)
* BaseOnWheels: At its most basic level, you could just slap some large rover wheels onto a Hitchhiker Storage Container and call that a base. Anything more elaborate depends on your imagination and engineering and piloting skills – and mods.
** Man contracts require the bases to be mobile, because they’re easier to assemble into larger structures that way.
* BeautifulVoid: Only one planet in the whole system has ([[TooDumbToLive debatably]]) intelligent life [[spoiler: although there is evidence for it on others]], and even that planet is mostly empty aside from your Space Center and a few other locations of note (as of 1.02). [[http://forum.kerbalspaceprogram.com/showthread.php/40374-WIP-KerbTown-v0-13-Beta-Place-static-buildings-cities-launch-sites-more!?highlight=KerbTown Some particularly enterprising modders]] are working to make the place feel more lived-in, literally.
* BeyondTheImpossible: It's supposedly impossible to land on the gas giant, Jool, ''because it's a planet that's made of gas''. Yet the player can do so anyways. The sensors recommend that you don't think too hard about it.
* TheBigBoard: Both the Tracking Station and the in-flight map view allow you to see statistics on the various bodies in the Kerbol system and monitor the progress of your active flights.
* BilingualBonus: The Kerbal language is Spanish, played backwards and sped up.
* BillionsOfButtons: Inverted for comedic effect. Kerbals have a joystick and a BigRedButton for commanding the modules, and... that's about it.
** Obviously, the modders were right on it, with cockpits based around [=RasterPropMonitor=] are sufficiently instrumented for all-IVA flights.
* BodyHorror: Kerbals on [=EVA=] can suffer from [[http://vignette3.wikia.nocookie.net/kerbalspaceprogram/images/c/c6/Krakenkerbal.png/revision/latest/scale-to-width-down/398?cb=20141011170415 somewhat]] [[http://i.imgur.com/EeIXnPs.png disturbing]] [[http://i.imgur.com/Ay9GDDz.png glitches]] when subjected to extreme forces.
* BoringButPractical: As it also slides into DifficultButAwesome, the SpaceshipSlingshotStunt is this due to its practicality of saving fuel for a round trip instead of directing expenses at the target. While this move is as promising as it should be, the process as a whole is boringly tedious since it requires several roundabouts around gravity wells, namely planets, to gain enough speed to reach out to others, a lot of timeskips usually ensues.
** [[TheTaxi Ferry missions]] in Career mode. Sending tourists into orbit around planets and return racks a sizable amount of cash, especially in large stable munarbuses for maximum efficiency.
** Vehicular Space Diving, done by throttling retrograde at full speed until orbital velocity around a planet becomes nil allowing the ship to descend with its own gravity well. This is essentially a ColonyDrop but without the consequence of being burnt out by re-entry friction from horizontal velocity, though usually this is done with ships that have extra fuel.
* BoringReturnJourney: Averted. Returning to Kerbin from another planet is usually just as challenging as getting to your original destination was, and often more so if you're low on fuel and have to get creative...
** Almost any return to Kerbin involves aerobraking, which is not FrictionlessReentry and is quite dramatic.
* BrickJoke: Just about all the science parts warn you in their descriptions that the "warranty will be voided if X happens" (X usually being a mundane or obvious use for the part). If you somehow manage to land on Jool and run a seismic scan, you get the following message:
-->The sensor has informed you that the warranty has just been voided. No refunds.
* CameraPerspectiveSwitch: If your rocket has a manned cockpit, you can switch to an Intra Vehicular Activity camera and experience the ride from the inside. Many players fly entire missions from the IVA perspective as a SelfImposedChallenge.
* CaptainCrash: Building your own vehicles is one thing, landing them is another. Mun Landings, for instance, often end in the vehicle tipping over and falling to pieces, leaving the Kerbonauts stranded until help arrives (or backup help when the help befalls the same fate).
* CelebrityParadox: At various locations in the solar system, you can find [[spoiler:giant monoliths]] with the Squad logo on them. This seems to imply that the game devs exist in-universe as some sort of {{precursor}} species.
* CentrifugalFarce: Featured in the [[http://youtu.be/dlbHmsHOe-U 0.21 release trailer]].
* ChestOfMedals: A series of service ribbons with a host of devices are available for use in signature lines on the KSP forums, indicating what planets you've been to and what you've done there. There is even a mod that tracks the careers of your Kerbals in-game, updating their ribbon and medal counts using the same criteria.
* CloudCuckooLander: Jebediah Kerman, who always smiles all the time, no matter what is happening. Unless [[StuffBlowingUp something]] goes [[HolyShitQuotient wrong.]]
* ColonyDrop: The introduction of the ''Asteroid Redirect Mission'' allows the player to attach ships to asteroids and redirect them to impact other celestial bodies. There is no particular reason to smash an asteroid at high velocity into a planet though, except as a SelfImposedChallenge. However, managing to safely ''land'' an asteroid on another celestial surface can give another opportunity for [[ForScience additional scientific data]].
* ConstructionIsAwesome: The game's primary appeal is that it lets you design, build, and fly your own spacecraft, space stations, and surface bases, including the possibility of assembling them part by part in orbit or on another planet's surface. See also DesignItYourselfEquipment.
* ContextSensitiveButton: Docking Mode allows you to use the normal rotation keys for RCS translation maneuvers, although it isn't strictly necessary as you can also translate from the main keyboard configuration using different keys. You can also define custom action groups when designing a vehicle, so that you can, for instance, press one key to extend all of your solar panels at once instead of having to do it one-by-one.
* ConvectionSchmonvection: Depends a bit on the circumstance. Engines dump heat into nearby parts, which can cause overheating if multiple engines or boosters are attached to the same part, but Kerbals standing directly in rocket exhaust don't seem to overheat. However, it is played straight when it comes to shedding heat: parts with lots of built-up heat lose that heat more quickly in thicker atmosphere, while parts in space take quite a while to cool down due to having no contacting fluid to pass heat into. A vessel close to something like the sun that has insufficient radiating surface area can actually find itself overheating from the small but continuous sunlight because there is literally nothing for it to have convection with.
* ConvenientlyClosePlanet: Averted, even taking into account the SpaceCompression. Even getting to the Mun is a challenge for the newest of new players, and traveling to other planets requires quite a bit of planning and forethought -- even more so if you plan on going home.
* CoolCar: Rovers are essentially meant to be Cool Cars In Space. [[TheAllegedCar Now, whether this succeeded or not is up to some interpretation...]]
* CriticalExistenceFailure:
** Your Flight Log may tell you that parts take damage from engine exhaust, but this damage seems to have no effect on their performance at all until they're destroyed outright.
** Overheating does not affect the performance of parts at all, until the overheating bar is full and the part vaporizes into a puff of smoke.
* DeathIsASlapOnTheWrist: Selectively averted with the 0.21 update, which allows you to enable permanent deaths for your pilots. You have to hire all of your astronauts, and when they're dead, they're gone for good. Previous versions of the game did play the trope straight, however, and you still can if you leave the option disabled (which is the default).
* DesignItYourselfEquipment: The full game comes with a small selection of prebuilt designs, but if you want to do anything really impressive, you'll have to design and build your own rockets, probes, satellites, etc.
* TheDevTeamThinksOfEverything: It's supposedly impossible to land on the gas giant, Jool, but they do have responses to performing science experiments on the "surface" such as the EVA report.
--> ''[[{{LampshadeHanging}} You're not sure how you even landed on the surface of a gas giant. But it's probably best not to think about it for too long...]]''
* DiegeticInterface: The vanilla game has virtual cockpits on the majority of crew pods, with an artificial horizon sphere, surface/orbit speed, vertical speed, and indicators for subsystems such as SAS. The [=RasterPropMonitor=] GameMod adds [[http://i.imgur.com/jaXqU5q.png multifunction displays]] to the cockpits, allowing you to play almost the entire game from first person - you can even get out of the [=MK1=] cockpit by pulling the canopy lever.
* DifficultButAwesome:
** The LV-N Atomic Rocket Engine is the largest and heaviest engine in its size category, has trouble with decouplers, and has one of the poorest thrust-to-weight ratios in the game. Its thrust is so poor that it is almost useless on any ascent stage, limiting it to final stages only, which because of the aforementioned weight and decoupling issues, takes a lot more effort to get into orbit than lighter engines - and good luck landing back on solid ground when the engines are twice as tall as any landing gear. However, if you can get them up there, they are ''the'' single most fuel-efficient liquid-fuel consuming engines in the game. They are one of the most popular options for interplanetary vessels for this reason.
** The First Contract (0.24) update makes this apply to reusable spaceplane designs. Designing and piloting them are both difficult to master, but the relative cheapness of fuel compared to parts and the fact that they can be piloted back to and recovered at the Space Center for a complete refund on their parts value makes them highly cost-effective for transporting crew, experiments, and small probes into orbit.
** Certain advanced maneuvers such as [[SpaceshipSlingshotStunt gravity assists]] or aerobraking can save a lot of fuel when done properly.
** Asparagus staging is a very efficient method of storing fuel because you can drop the added weight of empty fuel tanks easily and frequently. It also takes a lot of careful placement and tweaking to get it to perform correctly, or the rocket could easily become unbalanced or wind up ejecting full tanks. The multiple external fuel tanks can make for some unwieldy rocket designs too.
** With version 1.0 comes ore refinement equipment, giving the player the ability to mine ore then turn it into rocket fuel and monopropellant. Now you can keep rockets gassed up without having to expend any parts or performing additional launches. Except that both the critical components to this are very heavy and one of them is radially mounted which of course can lead to headaches trying to get the thing stable. The process will also usually require several specialized space ships to transfer fuel from the base then get it into orbit again. To cap this all off, in career mode (where rockets actually cost money and refuelling them is helpful) many contracts require using spaceships built after the contract was accepted, so you'll still have to launch new spaceships anyway.
* DiminishingReturnsForBalance: The amount of scientific benefit you get from performing the same experiment multiple times in the same environment slowly decreases until you end up getting nothing out of it at all. This is supposed to encourage players to send craft to many different environments, both around Kerbin and elsewhere in the system. Recent updates have made this effect even more pronounced.
** Happens in ship construction too, though this is more of a realistic effect than anything hard coded into the engine. Basically the larger a rocket is and the more boosters added (after a point), the less efficient the rocket becomes. This is mostly because the more fuel is added to a rocket in later stages the more fuel is consumed in earlier stages getting that fuel to where it needs to be. Using additional engines makes things less fuel efficient and adds weight that must be moved around. TheOtherWiki [[https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation explains here]]. This is a factor to snap the player out of the "big dumb booster" mentality and stimulate them to use more advanced shipbuilding technologies, such as orbital assembly and advanced, high delta-V engines.
* DisasterDominoes: Any accident that doesn't involve your rocket crashing into the ground wholesale usually involves these, and even that is often only the last domino in a chain of design and piloting mistakes.
* DisposableVehicleSection: Any multi-stage craft will be built this way, and completely {{justified|Trope}}. After all, getting to orbit requires a lot of propulsion and fuel, and once up there the empty fuel containers and excessively large engines just become dead weight. Any craft that averts this is called a single-stage-to-orbit vehicle, and depending on engineering and mission goal can range from AwesomeButImpractical to DifficultButAwesome.
** Some fan-made mods allow conversion of empty fuel-tanks into crew-cabins, laboratories, or other components, which makes construction of a space-station somewhat easier to accomplish.
* {{Dissimile}}: Eve's in-game description:
-->[Eve] is considered by some to be an almost sister planet to Kerbin. Well, despite the purple, and the toxic atmosphere, and the extreme pressures and temperatures... [[LampshadeHanging Actually, it’s not very similar at all is it? Who are these people?]]
* DoubleMeaningTitle: Likely occurs by accident. ''Kerbal Space Program'', being a computer game, is therefore also a computer '''''program'''''; in fact, it is a computer program that delivers an interactive simulation of Kerbals in space. [[ExactlyWhatItSaysOnTheTin So, ''Kerbal Space Program'' is indeed a Kerbal space program.]]
* DramaticSpaceDrifting: Can happen if a Kerbonaut on EVA runs out of fuel before he makes it back to the capsule.
* DrivesLikeCrazy: Several of the multi-ton cargo and utility vehicles in the Spaceplane Hangar are apparently driven by speed-obsessed maniacs, including at least one who loves to drift in circles around much larger vehicles and another who nearly causes a three-car pileup by trying to thread between two moving vehicles.
* DropPod:
** The one-person and three-person conical crew capsules are designed to be used as single-use reentry vehicles for your intrepid kerbonauts coming home from space -- with a parachute attached, of course.
** The addition of airbrakes in 1.0 allows players to slap them on Lander Cans to turn them into one-man drop pods. The airbrakes are powerful enough that only 4 are required to slow down a [=Mk1=] Lander Can from orbital velocity to a safe landing speed.
* DropShip: Possible to build - though ususally of the civilian variety, unless you take "conquering space" literally - and in many cases far more practical. Landers that detach from transition modules to go to a planet's surface and back are a common and practical example. {{Space Plane}}s that deliver small probes are another kind of example. Sometimes it is even possible to build an entirely [=VTOL=] design. [[https://www.youtube.com/user/CupcakesLanders Cupcake]] makes many good examples.
* EarnYourFun: Figuring out how to build a rocket that will actually achieve orbit, let alone go places, can be a challenge for new players. But this is a game that rewards persistence and a willingness to endure failure, and gives experienced players a universe of possibilities.
* EasilyDetachableRobotParts: With clever use of docking ports and probe cores, you can create completely autonomous spacecraft from modular components that can operate independently of the main craft as well.
* EasyLogistics: Individual craft have limited fuel and electricity, but (discounting monetary costs) that fuel is effectively in infinite supply for your space program as a whole.
** Also you never have to worry about food, water, or oxygen supply. This actually makes manned missions in some ways easier than unmanned ones (as unmanned command modules require electricity to run).
* EasterEgg: "Anomalies" scattered across the surface of Kerbin, Mun, and other bodies.
* EdutainmentGame: While the original game is not primarily designed as one, its creators support its use in the classroom as a teaching tool and have been working on a special edition called [[http://www.kerbaledu.com/ KerbalEdu]] specifically meant for classroom use. [[http://www.pcgamer.com/2013/05/30/kerbal-space-program-blasts-into-physics-classroom-as-an-end-of-year-project/ At least one teacher]] has incorporated it into his classes.
* EjectionSeat: It's possible to create a (very clumsy) ejection seat for rovers with the use of miniature [=SRBs=] and a decoupler. With the NASA update, a real-life equivalent from the Apollo program is available for regular cockpits - the [[http://en.wikipedia.org/wiki/Launch_escape_system Escape Tower]], a vectored SRB mounted on the top of the cockpit, which can be activated (in unison with a decoupler) in an emergency to lift the entire cockpit to safety.
* EmergentGameplay: Quite a few people find ways to have fun with the game without launching rockets into space at all, or by finding unusual uses for game parts. [[http://imgur.com/a/dhHfr#0 Geofley's]] [[http://www.youtube.com/watch?v=f5Sj-NX3aS4 Cove]], a fully aquatic base on Laythe, is one of the ''less'' outlandish examples.
** Another excellent example is [[http://forum.kerbalspaceprogram.com/threads/56621-The-Wrong-Brothers-career-mode-done-differently-%28pic-heavy%29 The Wrong Brothers]], in which a player goes through career mode using only the spaceplane hangar and runway, and never launches a single conventional rocket.
** Update 1.05 overhauled how buoyancy is treated in the game making it possible for some parts and even entire craft to sink. It is possible to build submarines and underwater bases, there are even contracts and records for them.
* TheEngineer: Engineer Kerbals, obviously. They can repack parachutes, fix broken rover wheels, and enhance the function of surface ore drilling equipment.
* EnormousEngine: The obvious result of sticking 2-meter diameter engines on 1-meter diameter fuselages or fuel tanks. More particularly, this is true of ''any'' launch vehicle, which is simply an enormous engine to get your (relatively) tiny spacecraft or probe up into orbit. Said launch vehicle tends to discard pieces after they are spent on the way up, gradually shrinking the size of the "engine" until only smaller ones remain.
* AnEntrepreneurIsYou: The 0.24 update introduces an economy system to Career Mode to provide funding and contracts for your space program.
* EpicFail: Half the fun of the game is watching your carefully crafted creations explode, go way off-course, or slam into Kerbin at hundreds of miles per hour.
** A classic and popular one is releasing launching clamps before activating engines. This can easily happen due to a buggy staging sequence. As the result, your majestic rocket will slowly fall to the ground, exploding stage-by-stage on contact, until all that remains is the crew capsule sitting in the middle of the launchpad empty save for the ring of the aforementioned launching clamps.
** Also, one that often occurs with single stage rockets with a parachute: the staging puts the parachute and the engine in the same stage by default, leading to the parachute deploying at the same time that the engine turns on, pulling the rocket sideways and into the ground.
* EscapePod: doable to various degrees, but can easily result in dead weight. Implemented as a mod by Umbra Space Industries: the [[FunWithAcronyms Deployable Emergency Reentry Pod]] is an inflatable one-man shelter atop a miniature propulsion block. It's still less insane than the real-life General Electrics [[http://en.wikipedia.org/wiki/MOOSE Manned Orbital Operations Safety Equipment]].
** On update 1.04, kerbals that contracts ask you to rescue now spawn in a lone command pod or crew module. What happened to the rest of their ship is anyone's guess.
* EverythingBreaks: Since the 0.25 update, the buildings of Kerbal Space Center are destructible if hit with enough force. [[VideoGameCrueltyPotential While potentially fun]], this is generally considered a bad thing as destroyed buildings cannot be used until the player coughs up the money to rebuild them (in career mode at least.)
* ExcusePlot: The plot is essentially "Have a rocket and a few astronauts. Now go into space." All the FlavorText for ship parts and mission contracts adds is "Everyone else is bad at going into space." You don't need to know why toy companies and canning factories need mineral scanners in a specific polar orbit of Moho.
* ExplosiveOverclocking: Cramming too many engines too close to one another and firing them all at full throttle is guaranteed to make them overheat rapidly. Let them get too hot, and all those engines will explode spectacularly.
* ExplosionPropulsion: While this is arguably true of ''any'' liquid or solid fuel rocket (no {{Orion Drive}}s in the unmodded game, yet) some players find creative uses for rocket exhaust:
** One common design {{Fan Nickname}}d the "[[Franchise/MassEffect Mass Relay]]" has two powerful rockets facing opposite each other, designed to go to full throttle immediately and simultaneously. Each rocket cancels the thrust of the other, but any object placed in front of one of the nozzles will be launched away at high speed. This is often used as a feature of space stations to move small masses without needing to have their own propulsion.
** And then you have [[http://forum.kerbalspaceprogram.com/threads/39947 the massive abuse of decouplers known as "Plaid"]], named for [[Film/{{Spaceballs}} how fast it goes]] (nearly 1 million meters per second - fast enough to reach the Mun in 13 seconds, or the Sun in 4 and a half minutes).
* ExpospeakGag: A few of these have crawled into the fan vocabulary from [[http://rocketry.wordpress.com/2011/11/13/rocketry-euphemisms/ real-world rocketry]], notably "rapid unplanned disassembly"[[labelnote:Translation]]The rocket suddenly breaks up in midair, usually because something exploded[[/labelnote]] and "lithobraking."[[labelnote:Translation]]The rocket "brakes" by hitting the ground[[/labelnote]] The latter [[http://en.wikipedia.org/wiki/Lithobraking is a legitimate landing technique]] that [[http://i39.tinypic.com/ofdb8.gif can be used in-game successfully]], but most of the time the term's used in the ironic sense.
* FacePalm: Gene Kerman (the guy at Mission Control) does this if you cancel a contract.
* FearlessFool: A common fan interpretation of Jebediah Kerman's personality. The description of him on his Steam trading card supports this.
-->"Fearless? Brainless? Who can tell?"
* FictionalCounterpart: Weird names and minor tweaks aside, [=KSP=]'s set of planets is essentially the same as ours. After a small, rocky planet and one with a very thick atmosphere, Kerbin is the third planet from its star, followed by a small red planet, then a small rocky object (the counterpart to [[http://en.wikipedia.org/wiki/Ceres_%28dwarf_planet%29 Ceres]]), then a huge gas planet with lots of moons, and so on. Saturn, Uranus, and Neptune equivalents are missing from the stock game, but do exist as a [[http://forum.kerbalspaceprogram.com/threads/104280-1-0-2-Outer-Planets-Mod-%281-7%29-CKAN-compatible-with-other-Kopernicus-mods-17-Jun mod]].
* {{Flanderization}}: According to the development staff, the attitude implied by, among other things, the use of the word "kerbal" as a synonym for "ridiculous and impractical" is a result of the fandom taking one aspect of the Kerbals' approach to rocket science and blowing it totally out of proportion. To quote [[http://forum.kerbalspaceprogram.com/entry.php/747-The-Making-Of-New-KSC this development blog post]]:
-->'''[=Bac9=]''': Overall, I'm convinced the obsession with disasters and perception of Kerbals as worthless engineers only caring about explosions is destructive for the game. KSP deserves much more than being a glorified disaster simulator where rockets falling apart and crews being killed is the prime entertainment and the only expected result.
* FlyingCar: [[http://youtu.be/QimxdqEWtC0 Rover wheels + rocket parts]] = HilarityEnsues. Skilled builders may elect to place wings, control surfaces and tailplanes on the car, in an attempt to make it more or less a [[http://youtu.be/KHSSoUnlCA8 proper flying car.]]
* ForScience: Literally in career mode, where doing experiments, sending reports, and collecting samples in various environments both terrestrial and extra-terrestrial accumulate science points used to unlock the TechTree. Generally, the further out from Kerbin you go and/or more inaccessible the location (Eve, for instance), the higher the multiplier for doing science becomes, thus "For Science!" is a wholly rational justification for conducting missions.
* FrictionBurn: A completely serious example, and one of the banes of players trying to make {{Space Plane}}s or aerobrake from a high orbit. Atmospheric heating due to compression, scaling with pressure and speed, can cause {{Overheating}} of parts. This means a vessel's speed has to be carefully monitored such that it doesn't incinerate in the air. Ironically, a blunter nose is preferable to a more aerodynamic one in this case (particularly if it has a high thermal capacity) because the physics simulation actually models a [[https://www.grc.nasa.gov/www/k-12/airplane/detach.html detached shockwave]], putting less stress on other parts.
* FrictionlessReentry: Played straight during development. Oddly, scary-looking reentry flames were added early on, but for a long time they were purely decoration; you could still plow vertically into the atmosphere at interplanetary speeds and survive unscathed. Fully {{Averted| Trope}} in version 1.0, which added the heat effects from re-entry that had been absent in the alpha and beta releases (unless you used the Deadly Reentry mod), though you can still turn off (or increase) the heat in the difficulty settings.
* FunSize: Kerbal proportions are quite odd compared to those of humans. For one, their heads are ludicrously oversized.
* FunnyBackgroundEvent:
** One of the engineers in the rocket assembly area randomly hits the floor with his hammer.
** Some of the engineers are carrying [[CowTools tire irons]] around.
** The large group of Kerbals in reflective vests and carrying lighted batons, doing... Well, it's not really clear. Semaphore lessons? Yoga?
** On the Munar loading screen, an empty helmet will sometimes roll across the Mun's surface in the distance.
*** And now we know [[http://youtu.be/hUjGW2htpR4?t=58s how it got there]].
** A sandcastle on the Mun can sometimes be seen in the background.
** The service trucks added in 0.21 to the VAB and SPH drive around, but you will occasionally see the trucks [[MultiTrackDrifting drifting.]]
* FutureCopter: Any air-breathing stock [=VTOL=] will necessarily be this. As the stock parts have no rotatory wings, the only way to have any upward thrust is via downward-vectored engines, typically jets.
* GameBreakingBug:
** Earlier versions of KerbalSpaceProgram used to have a few of these; most of them have been fixed in more recent versions.
*** If you attached your engines directly to the large orange fuel tank, it had a nasty habit of causing said engines to overheat much faster than normal. This could be fixed by adding a smaller fuel tank to the bottom and taping it up with struts, or by using two half sized fuel tanks instead.
*** When RCS thrusters were first added, they were programmed to have more thrust when they were closer to the ship's center of mass. Since there wasn't any cap on this, having an RCS thruster dead on the center of mass would give it infinite thrust, crashing the game.
** Landing physics, especially when high impact speeds are involved, can be dicey. For example: trying to land on Jool [[http://youtu.be/Kkeb5-u3-lY?t=2m35s causes the entire solar system to disappear]], crashing a pole of incredibly tough struts [[http://youtu.be/NLscXyIP4c8?t=1m52s destroys the planet you crashed into]] [[http://youtu.be/NLscXyIP4c8?t=2m33s (unless it's]] [[EldritchLocation Jool)]] and even trying to create an artificial ring around the planet [[http://youtu.be/iNr9c4vUp6s?t=2m45s would cause the ground to disappear]].
*** Trying to make a new jetpack design with the external seats? [[http://www.youtube.com/watch?v=30-SDAjIqLI Bye-bye, Kerbin]]!
** The game has picked up a reputation for devouring memory, especially if mods are added, as the game ''must'' load every single asset into memory upon starting. Viewing the Space Center causes memory usage to increase, and it will increase with every successive view. Nasty memory leaks crop every once in a while, such as the part overheat gauge in version 1.0.0 causing the game to crash within minutes once a part starts to overheat. Starting version 1.1 these bugs should be all but eliminated with the new 64 bit {{Unity}} engine.
* GameEngine: Built with UsefulNotes/{{Unity}}3D.
* GameMod: The game is extremely mod-friendly, and several mods have been directly incorporated and their makers hired on as developers. One of the fanbase catchphrases is "There's a mod for that", since there are ''so many'', from autopilots to improved visuals, from vital features the devs haven't got around to yet, to fun and wacky parts like soccer balls.
* GameplayAutomation: The "[=MechJeb=]" user-made addon adds an autopilot feature to the game. Since each autopilot program is a separate "module" (with one for docking, one for ascent, one for rendezvous, etc), it's the player's decision how much they want to automate their flight.
* GuideDangIt: One of the game's few flaws is that there is little in-game documentation of how most things work. You'll have to learn either by a lot of trial and error, by reading up on and applying actual rocket science, or by watching tutorial videos on [[YouTube YouTube]]. In version 1.1 and onwards a "[=KSPedia=]" in-game information system should remedy this.
* TheHardHat: Kerbonaut helmets are apparently hard enough to survive impacts that would otherwise kill the wearer.
* HilarityEnsues: Common in the official promotional shorts, most of which involve some poor kerbal suffering AmusingInjuries by ignoring some basic rule of spaceflight safety.
* HitboxDissonance: In older versions of the game, a few of the buildings at the Kerbal Space Center had some wonky collision meshes, such as the SPH being about 10 meters taller than it actually appeared to be.
* HouseRules: Prior to implementation of a proper campaign mode, some users had created and shared their own systems for handling funds and tracking pilot stats as a SelfImposedChallenge.
* HumbleBeginnings: The original "Kerbal Space Program" was [[http://forum.kerbalspaceprogram.com/showthread.php/8995-I-have-found-it!!-THE-ORIGINAL-KERBO-LOG! the background for a series of model rocket launches]] by the developers when they were teenagers. More than a decade later, they decided to use the idea as the basis for a video game.
* HumanResources: The "Kethane" GameMod comes with the KE-WAITNONOSTOP-01 Kerbal Unreconstitutionator, which can recycle Kerbal astroanuts into kethane (to refine into fuel)
* HurlItIntoTheSun: Perfectly possible, [[RealityEnsues but by no means easy]]. Doing so from Kerbin orbit requires at least four kilometers-per-second of delta-v, and that is including a SpaceshipSlingShotStunt, or twice the amount of delta-v without one. Just getting there is a major SelfImposedChallenge for some players, though getting a close flyby (by astronomical standards) can be a big boon to science in career mode.
* ImprobablePilotingSkills: Often times directly proportional to the improbability of the craft.
* InfiniteSupplies: Kerbals do not require oxygen, food, or any other supplies and can [[PerpetualMotionMonster run literally forever]]. Averted for the various rocket fuels, which ''will'' run out and forms the basis for the game's difficultly.
* InterplanetaryVoyage: No science-fiction technology for you -- if you want to explore the local solar system, you have to do it the old-fashioned way, with rockets and orbital mechanics.
* InSpaceEveryoneCanSeeYourFace: Kerbonaut helmets don't have mirrored reflective visors. This is presumably so that the player can get a kick out of watching their expressions change [[OhCrap when something]] [[GoneHorriblyWrong goes horribly wrong]].
* InUniverseGameClock: "Internal Game Clock" variety. Time normally passes in real time and is recorded in Earth minutes, hours, days, and years (with, since 0.23.5, [[AlternativeCalendar an option to switch to Kerbin days and years]], where each day is 6 hours and each year is 426 days). Thankfully, as some missions could take a very, very long time in real-time, there are options for time acceleration. Each planet and moon has its own day-night cycle determined by its motion within the solar system, which is important when planning landings or using solar-powered probes.
** HitSoHardTheCalendarFeltIt: Whatever the reason, the game always starts on Year 1, Day 1, 0:00:00. Which just so happens to be the middle of day in the Kerbal Space Center.
* IDontKnowMortalKombat: Aside from the abovementioned Lu fiasco, there is noticeably little use in remodelling the real-life Lunar Orbital Rendezvous system in the game’s miniaturized environment. The mass of the additional engine, the Mk 2 Lander Can, the supporting electrics, the manoeuvring engines and fuel for them, and the docking port – all in all, another, albeit lighter, spaceship – does not justify the delta-V savings from not having to take the return fuel up and down the gravity well.
* InstantCostumeChange: Jeb, Bill, Bob, and Val have orange spacesuits while inside a pod, but when they go on EVA [[OffscreenRealityWarp their suits magically turn white]]. To add further confusion, they have orange EVA suits in promo material and even the loading screen images, [[GameplayAndStorySegregation but never in unmodded gameplay]]. The other, randomly-generated kerbals wear white suits at all times.
* IronButtmonkey: As long as the Kerbals are not killed outright, they can come out of some spectacular disasters none the worse for wear, allowing for some serious VideoGameCrueltyPotential (see below).
* JetPack: Every Kerbonaut has an EVA pack to prevent him from floating away from his vessel. It only works as a traditional jet pack on low gravity bodies, though on the smallest objects, it is possible to achieve orbit. It has 20x the fuel of a real life jetpack.
* LensFlare: You can see the effect whenever your camera is pointed towards the sun.
* LittleGreenMen: The Kerbals are green, and approximately 0.75 m tall.
* LoadsAndLoadsOfLoading: This will definitely happen if you have a low end computer, or if you have a 3,000-part ship being put on the pad.
* MadeOfExplodium: Rockets have a habit of blowing up on occasion, usually during stack separation or when insecurely radial-mounted pieces "wobble". Justified by most of a rocket's volume being fuel containers which in turn hold most of the rocket's mass... mass that is itself a two-part combustive compound designed to explode preferably slowly and in a controlled manner. Pretty much [[EveryCarIsAPinto Every Rocket Is A Pinto]].
** Every single part, regardless of function, will explode when it hits the ground with enough force.
** Starting with 0.25, all of the buildings at KSC explode and get destroyed in a fireball if hit with enough force. The water towers appear to be filled with Kerosene.
* MadeOfIron: In contrast to the MadeOfExplodium rocket parts, Kerbonauts are incredibly durable. Besides never running out or air or needing food or water on multi-year space journeys, they can somehow survive crashing into the ground at up to 45 m/s (about 100 MPH) completely unharmed. Your ship's landing gear will snap off and/or explode at one-third that speed.
** It's been speculated that it's in fact their ''helmets'' that are MadeOfIron. Landing a Kerbal on their legs will generally kill them instantly, but if you flip them over and land them on their [[TheHardHat helmets]], it's ''possible'' to survive.
* TheManyDeathsOfYou: Blowing up in liftoff, drifting into the void of space to starve or freeze to death, spinning madly on the launch pad, hurling yourself into the ''sun'' - there's no end to the creative ways these guys can perish.
* MeaningfulName: As mentioned under Aerith and Bob, some of the randomly generated names are {{Shout Out}}s to real-life people (like [[http://en.wikipedia.org/wiki/Buzz_Aldrin Buzz Aldrin]] or notable KSP lets-players). Furthermore, Valentina Kerman is named in honor of Soviet cosmonaut [[http://en.wikipedia.org/wiki/Valentina_Tereshkova Valentina Tereshkova]], first woman and first civilian in space.
* MechanicalHorse: [[http://www.youtube.com/watch?feature=player_embedded&v=6jD9hbcCyxA Yes, you really can build one]]. It's entirely made from stock parts, too.
* MohsScaleOfScienceFictionHardness: 5.5. While the game uses realistic Earth technology and Newtonian physics, it is also meant to be accessible to the average Joe and used as a teaching tool, which softens it up a bit. Think of it as being able to fly really cool model rockets that can land on other planets.
* MoneyForNothing:
** In the early game, it's difficult to make money. However, once you reach orbit, many contracts with easily fulfilled objectives (rescue missions, science data from space, etc) open up allowing for MoneyGrinding. Unless you build seriously over-engineered rockets, you will ''always'' turn a healthy profit on contract missions, turning out huge sums of moola to spend on silly and/or expensive endeavors.
** The other "currency," science points, follows a similar trajectory. Early on, it can be hard to grind out enough points with your limited part options; but once you can get to the Mun or Minmus with a bunch of experiment parts, you can easily gather enough science to unlock everything by visiting all the biomes on the moon(s). Then you can use those parts to visit other planets and get vast amounts of additional science... and have nothing to spend it on. Science can be exchanged for money, but, well, see above.
* MotherShip: This is probably one of the most popular and efficient methods of inter planetary travel. Even if the mother ship in question isn't reusable, its still a lot more efficient to bring a big ship that can deploy a lot of probes than to just repeatedly send probes to almost the exact same place, or to cart interplanetary vessels to and from the planet.
* MundaneDogmatic: No aliens (bar the kerbals themselves), and all technology present is equivalent to modern-day or near-future / in-development rocket tech.
* NervesOfSteel: Jebediah Kerman almost ''never'' loses his cool. If you can get him to [[NotSoStoic crack]], the odds are good that your spacecraft is already doomed.
* NintendoHard: The game is pretty harsh and unforgiving if you don't know what you're doing; most new players take a while to achieve their first orbit, partly because of [[https://what-if.xkcd.com/58/ common misconceptions about how real rockets reach orbit]] (you don't need to go up very far, but you need a tremendous amount of ''horizontal'' velocity). Even if you've mastered the game, a single mishap can ruin that epic Jool mission you poured hours into.
** While building finely balanced, efficient rockets and sending them to other worlds may not be particularly easy, this pales in comparison to trying to build a Single Stage to Orbit (SSTO) space plane and docking with your orbiting space station. [[SchmuckBait Seriously, try it!]]
* NoAntagonist: The only obstacles to your progress are your own design or piloting mistakes. That and the harshness of space.
* NoOneGetsLeftBehind: A popular form of SelfImposedChallenge is to always, ''always'' make a rescue attempt for any Kerbonauts stranded far away from home unless they're plainly lost to the clutches of space. See VideoGameCaringPotential below.
* NoOSHACompliance: Parachutes, landing gear, or anything to insure the survival of your Kerbals are entirely optional. It is even possible to make rockets that face ''down''.
* NoPlotNoProblem: There's no real story or backstory to the game aside from player fanon. There's just you, your space program, a ton of rocket parts, a solar system filled with planets and moons, and an endless supply of eager would-be rocket jockeys.
* NoPronunciationGuide: The [[http://www.reddit.com/r/KerbalSpaceProgram/comments/2n8fja/how_do_you_pronounce_mun/ pronunciation]][[http://www.reddit.com/r/KerbalSpaceProgram/comments/1ugiq0/how_does_everyone_pronounce_mun/ of the]] [[http://wiki.kerbalspaceprogram.com/wiki/Mun#Trivia Mun]]
* NotTheFallThatKillsYou: It's entirely possible to survive a fall that would be fatal by simply ''landing on your head''.
* NotTheIntendedUse: See EmergentGameplay above. For example, since fuel tanks are buoyant, you can build rocket-powered speedboats with the right parts.
* OhCrap:
** Bill & Bob Kerman always look worried whenever the spacecraft is doing anything other than holding still. ''All'' characters do this if something explodes. If Jebediah ever stops grinning... see above.
** With the addition of other Kerbonauts, it has been revealed that each one has a personality based on certain modifiers, which in turn determines how brave or cowardly each one is. One of these modifiers is if the Kerbal is trained as a pilot or not (either yes or no). If he is a pilot, he will be mostly happy. If not, he will scream his pants off.
** Bob will always look ''terrified''. He'll only calm down if the craft is confirmably drifting back to the surface slowly via parachute or has come to a complete, safe stop.
* OmnidisciplinaryScientist: Science Kerbals have no specialization, they are all experts in generic [[HollywoodScience Science]]! They can clean out and refurbish otherwise expendable experiment modules, enhance the degree of science gained from experiments, and staff laboratory modules to conduct longer-term research. There is, at least, a distinction between scientists and engineers.
** The basic science devices are also like this. One is the "Science Jr.," a big cylinder full of nondescript "samples" that react to their environment, and the other is a tank of "mystery goo." You can research more specific tools, like thermometers and barometers.
* OneGenderRace: All Kerbals appeared to be the same gender while the game was in beta. Averted starting with 1.0.
* OrionDrive: Via a GameMod [[http://www.projectrho.com/public_html/rocket/sealofapproval.php#id--Computer_Simulation--Kerbal_Space_Program--Orion_nuclear_pulse made by]] the webmaster of the hard science website ''Atomic Rockets''. In true Kerbal fashion, the first test fire of the drive caused the command module to go flying off the top of the ship like a cork on a wine bottle.
* OutsideRide: Kerbonauts can ride on the outside of rockets by holding onto ladders, but they don't have especially strong grip (so be careful if you try it yourself and ''never'' try it when the craft is accelerating). Version .20 added seats; see RocketRide.
* {{Overheating}}: A mechanic in the game is a realistic modeling of heating effects. Different parts have different heat tolerances, with separately tracked values for internal and surface heat, and radiate heat differently depending on atmospheric temperature and pressure. As expected, radiating heat is very slow in space. If the built up heat exceeds a given part's threshold, it experiences a CriticalExistenceFailure. Some of this heat can be managed with additional radiator parts to help cool it, just make sure none of those radiators are facing prograde during atmospheric entry, because [[FrictionBurn their heating flux works both ways]].
* OvershadowedByAwesome: [[https://www.youtube.com/watch?v=5GXFzMnCWBs Dres.]] Most people have never heard of its real-life equivalent, Ceres, giving it a disadvantage from the start. It looks almost exactly like the Mun, and lacks any planetary personality--Moho is closest to the sun, Eeloo is farthest, Eve is very difficult to escape from, and Jool has several moons with various quirks. Dres is just a gray rock in an uninteresting location. It has neighboring asteroids, but so does Kerbin. Dres gets so few visitors that the challenges forum has a "Dres Awareness" project, to encourage players to send epic missions to the poor neglected planet.
* PerpetualMotionMonster: If one were to dump Valentina on the Mun with nothing more than her spacesuit, she could sit there until the heat death of the universe. They also have infinite stamina, and they can shrug off any amount of G-forces. Various mods force you to feed, water, and/or oxygenate your Kerbals, but in the stock game they can only die from high-speed impacts or incineration, much like inanimate objects.
** Before the introduction of re-entry heat, if one had the EVA Parachutes mod, it was completely possible to [[https://youtu.be/iDLBTvpzf_s?t=508 perform interplanetary EVAs]].
* QuicksandBox: The game can be unforgiving sometimes, but fortunately there are a wealth of videos and forum threads out there to help, and there's plenty of fun in trying to figure out what gets out of atmo without ripping itself apart.
* RagdollPhysics: If a Kerbal hits something at high speed (but not fast enough to [[OneHitPointWonder die instantly]]), they go into ragdoll mode, flopping around helplessly and often [[BodyHorror violently]] until they tumble to a stop. This doesn't cause any permanent injury, somehow, but can be pretty irritating if they fall down a mountain and you're forced to wait several minutes in real-time before you can control them again.
* RealityEnsues: You may spend hours recreating a ship from your favorite sci-fi story only to find that it flies like a brick in the air or spins uselessly in zero-g... or tears itself apart as soon as you put the throttle up.
** Also, sure you can build a nice GlobalAirship to visit all the cool easter egg landmarks around Kerbin. You also have to take the time to sit around and fly it yourself, plus land it without crashing.
** There is a steep valley on the Mun that was added in one of the patches. Naturally when this was discovered, the first thing the fanbase did was fly there to recreate the [[AerialCanyonChase Death Star run]]. This turned out to be much less exciting with real world physics (and without enemy gunfire, as well). All you need to do is create a low enough orbit to pass through the canyon, cut engines, and gently thrust away from the walls.
** Wait, there's [[AsteroidThicket asteroids now?]] Awesome, let's go make like Han Solo - Oh, wait, they're ''millions of miles apart''.
* ReentryScare: With heating introduced, this is a justified state in some cases, especially if you’re dealing with a spaceplane, which doesn’t just have an ablative heat shield.
* RidiculouslyFastConstruction: A non-RTS example. Unlike real life, craft have no lead time whatsoever. No time passes when in any of the buildings, including the VAB or SPH, so a craft can go from conception to the launch pad in 0 seconds of game time. So it's entirely possible to have a Kerbal on the mun 2 days after the space age begins (assuming you know how to build the craft). It also means that a kerbal trapped in space can be rescued in a matter of days, if not hours. Some mods avert this by adding realistic construction times once the craft is designed in the editor.
* RefiningResources: Version 1.0 added ore that can be mined across various planets, and scanners to detect concentrations of it. This can allow refueling as ore can be converted to fuel, however, this can be hard to do at times as both the drill and the converter are rather large.
* ResourcesManagementGameplay: While the Career mode has to deal with reputation, science, and funds on the strategic level, every gameplay mode has to deal with resources on a mission level. These include number of crew, electric charge, reaction control propellant, and ''especially'' fuel (crew support like oxygen and food are [[AcceptableBreaksFromReality thankfully]] [[EasyLogistics infinite]].) Since sending more of these things into orbit requires expending them in ever greater quantities, there are seriously diminishing returns for trying to take more with you, so efficient use of them is necessary.
* RetroRocket: It's not ''impossible'' to build and operate a reusable SSTO "tailsitter" rocket like the trope depicts, merely [[RealityEnsues very, very difficult]]. Having a fueling station at the destination or in-built ISRU capabilities are highly recommended if you want to make it somewhat practical for more than just quick orbital or suborbital hops. On the other hand, many rockets will look retro on takeoff, but will most definitely shed parts on the way up.
* RocketlessReentry: Technically possible in older versions of the game; the trick to it involved [[ViolationOfCommonSense landing them]] [[HardHead on their head]]. The addition of reentry heat essentially ended the practice.
* RocketRide: 0.20 introduced official support for seats, mainly intended for rovers. Of course, sticking one to the side of a large rocket and launching it into the stratosphere was one of the first things a lot of users did.
* RuleOfFun: [[WordOfGod Squad's response]] when anyone asks them if they will do anything to make the game more realistic is "Would that make the game more fun?" If they think it will, then they will try to incorporate it, and if not then [[AcceptableBreaksFromReality they will let it slide]]. Some things are intentionally unrealistic for the sake of fun; the entire universe has SpaceCompression applied because using real-life scales would make climbing to orbit and reentry/landing rather tedious.
* SciFiWritersHaveNoSenseOfScale: The developers avert this but the use of this trope in media has caused some confusion among players less familiar with actual astronomical scales. Even among those familiar with space flight don't always remember exactly how big space really is. For instance, some have suggested ignoring time acceleration (i.e. being able to increase the speed of the game) and instead allow the program to run essentially in the background to allow for realistic flight during extended missions. Even acknowledging that a single mission would very well be months long, they don't seem to realize that most of that time would be spent doing... nothing.
** The distances are less than they would actually be, but that's due to the SpaceCompression. The scales for Kerbin/Mun/sun are roughly the same as for Earth/Moon/Sun accounting for it.
* SelfImposedChallenge: Making ridiculous rockets, making manned ballistic missiles, making space shuttle equivalents, spacecraft that look like specific patterns, achieving orbit, reaching relativistic speeds, getting a huge and completely pointless concrete cube into orbit, landing on the moons of Kerbin, landing on other planets, landing on ''the sun'', flying to the North Pole, flying to the other Space Center, etc.
** There is an entire ''[[http://forum.kerbalspaceprogram.com/forums/26-Challenges section]]'' of the official forums dedicated to [[InvertedTrope imposing challenges on other players]].
* SeriesMascot: Due to his MemeticBadass status, Jebediah is the most recognizable of the Kerbonauts.
* ShoutOut- Often found in the equipment part descriptions
** The tiny size of the "LV-1 Liquid Engine" is mocked with [[Film/{{Zoolander}} What is this, an engine for ants?]].
** The "Advanced Grabbing Unit" is otherwise known as [[WesternAnimation/ToyStory The Klaw]].
** If opening up a materials bay doors for science over Jool, the science report will tell the story of the computer saying [[Film/TwoThousandOneASpaceOdyssey "I'm sorry, I can't let you do that"]] and then [[OhCrap hurriedly complying]] when you [[AppealToForce head to the fusebox]].
** The release notes for the 1.0.5 update has the following comment: "Kerbals have the added advantage of not requiring any [[Literature/TheMartian potatoes for unplanned long-duration stays on desolate planets]]."
** The PB-NUK Radioisotope Thermoelectric Generator generates a small, steady charge indefinitely, but it should not be [[Literature/TheMartian used on rover excursions to provide heat.]]
* SimpleYetAwesome: Encouraged by the Career mode introduced in the 0.24 "First Contract" update. Each rocket part now costs funds, of which the space program only has so much at any one time, making simple rockets with inexpensive and easily recovered and refurbished parts necessary for accomplishing elaborate objectives, where an unrestricted mode might favor flashier and less humble designs.
** Once the appropriate technologies are unlocked, other options become available. Simple designs can be hard to recover, but complicated [=SSTOs=] for low-orbit missions may actually save more money - [[DifficultButAwesome provided the player is able to bring them back to the runway in one piece]].
* SimulationGame: It's not on the same realism level as ''VideoGame/{{Orbiter}}'', but it's realistic enough to be a great way to learn basic orbital mechanics.
* SingleBiomePlanet: Zig-zagged during development. Kerbin up to version 0.17 was mostly grassland, with the exception of the poles, which were icy. 0.18 and above added rivers and deserts. Version 0.22 and 0.23 added a variety of "biomes" to Kerbin, the Mun, and Minmus, which will give different research data when experiments are performed within them. Finally averted in 0.90, which added biomes to every celestial body in the solar system (except the sun and Jool).
* SlapstickKnowsNoGender: Valentina Kerman and the other female Kerbanauts are no more explosion-proof than their male counterparts.
* SoftWater: Averted. A hard splashdown can outright destroy a spacecraft and its unlucky passengers.
** In fact, splashdowns are often actually more dangerous than landings on solid ground, since when a spacecraft hits the water, it doesn't slow down very quickly. Consequently, all or most parts on it must pass a check to see whether or not their actual splashdown velocity exceeds their rated maximum impact velocity. If it does, they're destroyed. Often, this leads to oceans swallowing up entire spaceships, leaving only a few high-impact-tolerance girders or decouplers bobbing in the water. By contrast, when a spaceship impacts land, the first parts that hit the ground absorb some of the impact velocity and it decelerates much more quickly, giving parts (and crew) far away from the point of impact a chance of survival.
** The 1.05 update made water, while not soft, at least soft''er'', by giving the simulation a new buoyancy model. Craft that are properly shaped and hit the water at the right angle can certainly survive at velocities that might shatter less aquadynamic designs. Even seaplanes are viable if built right!
* SomethingNauts: Kerbal space explorers are called kerbonauts.
* SpaceCompression: To cut down orbit times and prevent the game from becoming [[IncrediblyLamePun astronomically boring]], Kerbin is a mere 1200km in diameter. Jool, the gas giant, is roughly the size of Earth. The orbits of planets and moons are similarly scaled down. All in all, the Kerbol system is roughly 1/11th scale... except for mass. Kerbin weighs about the same as Earth, meaning it's equally difficult to get to orbit on either planet, roughly.
** But if you want more realistic scaling, [[http://forum.kerbalspaceprogram.com/threads/55145-0-22-WIP-Alpha-Real-Solar-System-(Kerbin-Earth-rescale) there's a mod for that]].
* SpaceDoesNotWorkThatWay: Averted ''en masse''. Hooray science!
** Not counting certain glitches or the Space Kraken, of course...
* SpaceFriction: Averted; spacecraft obey Newtonian physics and will slow down only under power or when passing through an atmosphere. Objects that achieve escape velocity from the star will fly away into the infinite void.
* SpaceIsNoisy: Even in the depths of space, you can still hear rockets and explosions.
** Partially justified in that most of those explosions happen either in-atmosphere or when you're still attached to the thing blowing up/making noise, giving the sound a medium on which to propagate to your ears.
** Averted when using [[http://forum.kerbalspaceprogram.com/threads/56405-0-22-x-Atmospheric-Sound-Enhancement certain mods]].
* SpacePlane: Possible to build, [[EarnYourFun though not easy in the slightest]].
* SpaceStation: A basic space station isn't ''too'' difficult to put into orbit. Making anything elaborate is dependent on your docking skills, and the ability of your PC to load large numbers of parts.
* SpaceWhale: A very minor example, but one selection of music for when a ship leaves the atmosphere and enters space is unmistakably whale song. What this means is [[EpilepticTrees anybody's guess.]]
* SpaceshipSlingshotStunt: The game lets you pull off realistic gravity assists, both to gain a lot of speed or to shed it, depending on which side of the gravity well you try to sling around.
* SpeakingSimlish: Kerbals speak Spanish that is sped up and played backwards, making it almost unrecognizable. Contract messages are in English but may as well be in Simlish because it's all [[TheUnintelligible incomprehensible word salad gibberish]].
* SpiritualSuccessor: KSP can be thought of as a ''very'' distant descendant of ''VideoGame/LunarLander'', one of the earliest video games.
* StuffBlowingUp: If any part of a spacecraft hits the ground (or another part) too fast, it makes a nice explosion. The interesting thing is that parachutes and scientific equipment make the same explosion as, say, fuel tanks full of rocket fuel. These explosions seem not to harm other parts though.
* [[DuctTapeForEverything Struts For Everything]]: For the moment, the best solution to any problem involving the rocket coming apart is simply "Add more struts." This may change when the atmospheric drag model is overhauled in future versions.
** Can be significantly reduced by using a [[http://forum.kerbalspaceprogram.com/threads/55657-0-22-Kerbal-Joint-Reinforcement-v1-4-2-Properly-Rigid-Part-Connections mod]].
* SubsystemDamage: Each individual rocket part has its own parameters, including heat and impact tolerances. With a little luck, you can even save your crews from crashes that will destroy the rest of the vehicle.
* SuccessionGame: The [[http://www.youtube.com/watch?v=wVeadv54QPc International Youtube Space Station]], assembled by various players who contribute one module each.
* SuspendSave: While your game autosaves periodically to prevent blatant SaveScumming (not that it really needs to at this stage), there's also a single-use quicksave feature that allows you to save at various points during a mission so that you don't have to launch an entirely new rocket if your current one suddenly becomes a million-dollar lawn dart.
* SuspiciouslySpecificDenial: Found in the descriptions of various rocket parts:
** The X200-8 fuel tank is totally not a stolen swimming pool frame
** The Atomic Rocket Motor is harmless. [[Franchise/TheHitchhikersGuideToTheGalaxy Mostly.]]
** The scientific thermometer is totally not a store-bought model, and admitting that it is voids its warranty.
** Taken to extremes with the Not-Rockomax Mini Node, which is so obviously not a miniaturized version of an already-existing part that the (in-universe) manufacturers helpfully point out the [[BlatantLies complete lack of a resemblance]] in the name.
* TechTree: A feature of the game added in the .22 update. Kerbonauts and probes can now gather science in flight in Career mode, which you can use to research technology to unlock more parts.
* TertiarySexualCharacteristics: Female Kerbals have noticable eyelashes, longer hair, and a smaller more oval head compared to the males. But apart from that, they still have the same exaggerated body proportions.
* ThoseMagnificentFlyingMachines: The fanbase has made some strange contraptions that, against all odds, still fly. See GoodBadBugs.
** More particularly, any aircraft on Eve actually flies more easily than it does on Kerbin thanks to Eve's atmosphere being five times thicker, which makes even improbable designs workable. Especially since any such craft cannot functionally use jet engines due to the atmosphere lacking oxygen with which to power their internal combustion, and it must use other methods of thrust.
* TidallyLockedPlanet: Mun is tide-locked to Kerbin, Duna and Ike are locked to each other, and all five of Jool's moons (Laythe, Vall, Tylo, Bop, and Pol) are locked to their primary.
* TimTaylorTechnology: Fan lore is that almost any problem you have with a rocket can be solved with '''"MOAR BOOSTERS!!"'''
* TooDumbToLive: The numerous [[http://www.youtube.com/user/KerbalSPOfficial?feature=watch shorts]] Squad has made to advertise the game are filled with this behavior. The worst offender? One kerbonaut finds that a wrench he needs has somehow gotten into his helmet. So, he decides to take his helmet off to get it. While standing on the Mun. Which has no air. And another kerbal reacts to seeing the ownerless helmet rolling around by [[UpToEleven grabbing at his own helmet]] as if it might spontaneously come off.
* TooFastToStop: Docking accidents, flipped rovers with blown-out tires, "[[ExpospeakGag unplanned lithobraking]]"... There are ''many'' ways you can run into this trope in the game.
* TransformingMecha: Difficult in the base game, but the ''Infernal Robotics'' GameMod adds many servos and pistons to make transforming vehicles. More modest designs include spaceplanes with retractable powered wheels to function as a (clumsy) rover or alter their lift surfaces mid-flight for optimizing their behavior. More fantastic designs include a [[https://www.youtube.com/watch?v=4jPdEMwdLc0 replica]] of Starscream from ''Franchise/{{Transformers}}''
* TruthInTelevision: Sure NASA and the other space programs have brilliant engineers and scientists to build their spacecrafts, but sometimes things go a little Kerbal anyway. The tragedies are, of course, tragic, but those aside, here are a few more lighthearted examples:
** [[http://en.wikipedia.org/wiki/File:Shuttle_mounting_point.JPG This note]] painted on the Shuttle Carrier Aircraft.
** The Soviet N-1 Moon rocket with 30 engines on the first stage is [[http://www.aerospaceweb.org/question/spacecraft/russia/n1-1.jpg quite Kerbal]]. It is a result of a familiar issue of not having large-diameter parts, and spamming the smaller engines. It also experienced some rather catastrophic failures--in the the second launch attempt, it fell right back onto the launchpad, creating the largest man-made non-nuclear explosion in history. Similar disasters frequently happen to large Kerbal rockets because of inadequate struts or staging errors.
*** N-1’s competitor [[http://www.astronautix.com/lvs/ur700.htm UR-700]], never going off the drawing board, has a nearly unbeatable kerbalness quotient. All of thousands of tons of its propellants were the toxic, carcinogenic hypergolic fuels; it used the Direct Ascent principle popular among KSP players; it had not one but nine vertical stacks, because the designers wanted all the parts to be rail-transportable (which is much like a Kerbal player dealing with lack of sufficiently large parts); it had fuel crossfeed from the first stage into the second stage, also fired at launch; and its orbital stage had its own strap-on boosters.
** When training for the Moon landing, Neil Armstrong bailed out of the "Flying Bedstead" aircraft after losing control of it. His fellow astronauts were amazed at how unfazed he was by the incident. Fearlessly leaping out of a failing rocket in midair is a standard procedure for Kerbals (heck, they don't even bother using parachutes).
** Those who find rendezvous and docking to be difficult and counterintuitive may take comfort in the fact that early astronauts in the real world got off to a rocky start with it themselves. Gemini 4 was America's first attempt at having two different craft rendezvous in space. Unfortunately, neither the astronauts nor the ground crew fully understood the orbital mechanics involved, and so as they tried to thrust towards the target from a higher orbit, they ended up actually speeding ''away'' from it, which is completely backwards from how things are on the Earth's surface but makes perfect sense once you realize that they were thrusting into a lower orbit by firing against their own orbital velocity, which would make them orbit faster in the long run.
** The game's fandom (at least on the official forums) rejoiced on at least two occasions due to mentions from people who work in space science. The first was when UsefulNotes/NeilDeGrasseTyson tweeted that he thought the game looked fun and would probably spend "far too much time" playing it if there was a Mac version. (This resulted in the until-then low-priority OSX port becoming the absolute #1 priority for the devteam!)
** The second was, if anything, an even bigger reaction when, in response to a question on their blog, NASA's Curiosity Mars rover team stated that there were a number of people on the team who liked to play KSP during their free time. The unpaid endorsement by a group of REAL rocket scientists (or close enough to it for all practical purposes) set off tears of joy from the user base.
** Former Astronaut Ed Lu played the game with Scott Manley, [[IDontKnowMortalKombat Ed's first flight crashed in less than 30 seconds, the second got into space, but not into orbit.]] Despite not making it to orbit in-game, he still described it as "fun to play", which is pretty fair praise, too.
*** Ed Lu recently also appeared [[http://www.twitch.tv/ksptv/b/486895045 in a livestreamed interview with the KSP developers themselves]].
** A Falcon 9's [[https://youtu.be/_BgJEXQkjNQ?t=1m9s spontaneous combustion]] while sitting on the pad was a rare event in real life, but probably felt familiar to KSP players, since this can easily happen for a variety of reasons (too many or too few launch clamps, not enough struts, part clipping...). Some people joked that [=SpaceX=] should have pressed [[ResetButton "revert to VAB."]]
* UnexpectedlyRealisticGameplay: See also the entry for Art Style Dissonance. While it's fairly easy to build and launch a simple rocket, actually getting that rocket into orbit or to places other than Kerbin is fairly difficult if you're more used to less realistic space simulators.
* UnfinishedUntestedUsedAnyway: There's nothing that says you can't try to go straight for the Mun (or anywhere else) with a full crew in a rocket that you just built and aren't sure how it will perform. There are a few perfunctory checks to make sure that you haven't forgotten anything important (like parachutes for a safe return), but you're not even obligated to adhere to those. Fan lore is that the kerbal species as a whole is like this -- they're so excited about exploring space that they'll gladly strap themselves into the rockets they've built without bothering to test the design for flaws first.
* VideogameCaringPotential: Some players equip their crew capsules with not only parachutes but various other elaborate safety and/or abort systems, rescue all stranded Kerbals, and try to land returning ships as close to the Kerbal Space Center as possible...
* VideogameCrueltyPotential: ...while others take gleeful pleasure in sending the hapless trio to die in the cold blackness of outer space. [[StuffBlowingUp Or just blowing them up.]]
* VideoGameCrueltyPunishment: ... and then in career mode starting with 0.24, losing Kerbals will reduce your reputation, lowering the quality of the contracts that are offered to you because losing crew makes you look incompetent to investors.
* ViolationOfCommonSense: The best way to land a falling Kerbal? On their head. Their helmets can survive practically anything!
** With this in mind, you can usually save a Kerbonaut from a doomed aircraft by simply having him step out the hatch while low enough to the ground.
** You'd think the more advanced antennas would be better in some way, but they're actually ''worse''. In the stock game, the high-tech ones transmit faster than the basic Communotron 16; but a few extra seconds hardly matters when most space missions have days or even weeks of downtime, and the better antennas weigh more, cost more, and use more electricity. The devs do plan to fix this at some point, probably by limiting the range of the cheaper antennas.
* WeaponizedExhaust: An (often) unintentional example of using this on ''yourself'' if you are not careful with spaceship construction. All engines have heat tolerances which, when exceeded, will damage the engine. Too many engines too close together can overheat each other at full thrust, and other parts of the spacecraft too near the exhaust might be damaged as well.
** Also, if anything comes loose near a working engine, even a Kerbal, it will be launched off into the horizon at unsurvivable speeds, so standing near engines in general is not a good idea.
* WeHaveReserves: {{Lampshaded}} by the manual in the game itself, Kerbin consists of a virtually undepletable population of RedShirts dedicated to be substantially launched to anything that moves around the star system. [[AcceptableBreaksFromReality After all]], it wouldn't be any fun at all if you managed to run out of Kerbals to be flung into orbit.
** Despite of this, losing any of the original four orange suits[[note]]Like [[{{Badass}} Jebediah Kerman]][[/note]], provided with a PermaDeath option, they will be LostForever.
* WeirdMoon:
** [[http://www.reddit.com/r/KerbalSpaceProgram/comments/vwi0z/minmus_really_rustles_my_jimmies_long_w_science/ Apparently Minmus doesn't make a lot of scientific sense.]] The wiki has since been updated with a detailed and [[ShownTheirWork quite well-researched]] HandWave for most of its abnormalities.
** Laythe also has liquid water and surface temperatures that would let humans -and presumably kerbals- walk around near the equator with nothing but a [[GasMaskLongcoat warm coat and a rebreathing mask]], despite being much too far from the sun for this to be possible without some other mechanism. However, the developers have cunningly placed it in a Laplace orbital resonance with 2 other Joolian moons. The heating is supposed to come from the tidal interaction between these objects, in the same way that Io is kept hot enough to have volcanoes in our own solar system
* WideOpenSandbox: In Sandbox mode, money has no importance and there are no goals. 0.22 has added a rudimentary campaign with a limited selection of starting parts and the option to unlock more by researching your way up a TechTree, while 0.24 has continued to flesh out the campaign with funding and reputation systems to place additional limits on your space program. Even then there's no storyline as such, and you're free to do whatever you want within the limits of your available parts.
* TheWorldIsJustAwesome: With the improved facial reactions that have been introduced in 0.19, Jebediah Kerman can often be found gazing with almost childlike glee at the incredible sights around him. [[http://forum.kerbalspaceprogram.com/showthread.php/24533-Show-off-your-awesome-KSP-pictures! Many players are inclined to agree with him]].
* YesMan: Played with. No KSC worker bats an eye at the exploding machines of death you bring on to the launchpad, with the exception of some scientists, who will frequently stop and look at your rockets in horror before walking away in the VAB, regardless of how sound or unsound the design in question is.
* {{You ALL Look Familiar}}: All Kerbonauts of a given gender have the exact same face and haircut, as well as the last name of "Kerman." Whether they're all clones, a family of InexplicablyIdenticalIndividuals, or just members of [[DittoAliens a very homogenous species]] is a matter of some fan speculation. They aren't all ''perfectly'' identical, though, as they have individualized personalities determined by different levels of Bravery and Stupidity, as well as a hidden Pilot Training (or "[[{{Badass}} BadS]]") flag.
* [[YouCantMakeAnOmelette You Can't Make A Mun Landing ]] without blowing up a few rockets.
* YouHaveResearchedBreathing: Ladders and Thermometers are very high-end technology, as are support struts. It's okay however, you can get the science for it by finding out water is wet. Wheels come even later, along with command chairs, even though the basic command pod requires no research and presumably has a similar chair inside it. Lampshaded by the FlavorText for the "Electrics" technology:
--> Just for the record, we did know about electricty before rocketry. It's ''combining'' the two that's the big step forward!"
----
-->The sensor has informed you that the warranty has just been voided. No refunds.