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A science fiction {{tabletop RPG}} written by Kevin Crawford and published by Sine Nomine Publishing.

In the distant future, humanity has spread to distant stars with the spike drive, which allows hyperspace travel. Not ''easy'' hyperspace travel--fail to keep it under control and [[HyperspaceIsAScaryPlace your death will not be fun]]--but hyperspace travel nonetheless. While the [[VestigialEmpire Terran Mandate]] ruled the galaxy until a few centuries ago, a psionic disaster known as the Scream rippled across the galaxy and shattered society, [[ApocalypseHow killing massive numbers of humans and aliens and throwing the galaxy into chaos]]. [[BackFromTheBrink Only recently]] have ships begun to ply the space lanes again, and with the psionic-aided jump gates no longer usable, very little large-scale shipping between the systems is viable. Small groups of explorers scout out systems to find technology and resources left behind by the pre-Scream culture, and numerous factions wage war for dominance of their petty kingdoms. [[WideOpenSandbox It's up to the players to write their legends on this clean slate.]]

Of note is its [[{{Retraux}} retro-inspired]] [[WideOpenSandbox sandbox]] playstyle; it was written so that dungeon modules from other games could be grafted into a session with less than twenty minutes' work by, say, replacing Orcs with [[PigMan Hochog]] mercenaries and setting it on a space station instead of a dungeon complex.

A free version of the core book is available [[http://rpg.drivethrustuff.com/product/86467/Stars-Without-Number-Free-Edition here]]. Second Edition rules, which keep much the same lore but update the class and skill systems are available [[http://drivethrurpg.com/product/226996/Stars-Without-Number-Revised-Edition here]].

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!!Tropes present in the system as a whole:

* AfterTheEnd: Six hundred years ago, galactic civilization was shattered by the Scream, which killed or drove insane all psychics, whose powers were vital to the Mandate's infrastructure. New civilizations are rising on the former Rim worlds, but the galaxy remains a wild and dangerous place, many worlds have failed to maintain even the basic knowledge needed for spaceflight, and the glory days of mankind are past. ''Other Dust'' is the story of what happened back on Earth.
* AIIsACrapshoot:
** Why [[PsychoSerum removing an AI's brakes]] is ''always'' a bad idea in the long run. The [[RestrainingBolt programming blocks that slow an AI's growth]] also contain their ability to prioritize things or disregard irrelevant information, meaning that an unbraked AI [[InsaneTrollLogic regards all it sees as equally valid according to its internal logic]]. From there, it will devolve into a MadGod sooner or later; for example Draco, the first unbraked AI "god-mind", nearly turned human space into a totalitarian nightmare because of his BlackAndWhiteInsanity internal logic.
** There was ''one'' successful aversion of this, where [=AIs=] were able to develop beyond braked levels, but their relentless ethical and moral programming held tight. These seven beings were the Maestros, and before the Scream, they defended the Terran Mandate, often from its own evil.
* AnyoneCanDie: ''Stars Without Number'' does not believe in softball. There are pages that recommend turning up with spare character sheets, and first level characters are likely to die to a couple of bullets.
* ApocalypseHow: The Scream was Galactic, and its effects ranged from Societal Disruption to Extinction depending on circumstance.
* AppealToForce: In the opening fiction for ''Suns of Gold'', far trader Saif ibn Barakah deals with planetary Prime Minister Ivor Czarny in this way. He sold the people of Koszalin many advanced technologies in exchange for the planet's uranium, but when Czarny plans to expropriate his assets for the people, he reveals that he ''didn't'' sell Koszalin [[spoiler: technology to defend against nuclear weapons]].
* ArtificialIntelligence: It wouldn't be a sci-fi story without it. In this case, they're divided into three classes: "expert systems" that are basically specialized drones, "virtual intelligences" of roughly human intelligence, and true artificial intelligences with intelligence superior to humans [[AIIsACrapshoot at a dangerous price]].
* BlackAndGrayMorality: ''Suns of Gold'' explains that this is inherent in the system for far trade. Some planetary governments are grasping warlords or paranoid isolationists fighting to maintain power by controlling or eliminating trade, while others are trying to protect their world from revolutionary chaos caused by rapid technological importation and from the schemes of greedy merchants. Some far traders really want to bring back the prosperity caused by widespread commerce while making a fairly-earned credit, but even the best have to lie, cheat and steal to be able to continue trading. And some, as the book puts it, "are just unmitigated bastards."
* BrainUploading: Part and parcel of the transhumanism rules. The resulting mind-image ("soul", in the slang of the setting) can be loaded into an organic or robotic shell, ''TabletopGame/EclipsePhase''-style.
* CaptainSmoothAndSergeantRough: In ''Skyward Steel'', this is the expectation between officers and petty officers. Brawling, petty larceny and other disorderly conduct won't stop a skilled enlisted rating from climbing the ranks, and while they're expected to have gotten over this by the time they reach warrant officer, a warrant officer has also earned the right to be unsociable and impatient with rookies, especially [[EnsignNewbie rookie officers]]. An officer, however, is expected to be above disorderly conduct and fraternization with the men, instead being upper-class, educated, and inflappable come what may.
* CargoCult: Perimeter Agency installations are a version engineered by the Mandate. They adhere to their anti-maltech mandate with literally religious devotion because the catechism of the Agency ("the Vow") is built into the mechanisms that allow them to use their pretech devices and fabricators. Even when the planet has fallen so badly that they don't know what maltech ''is'', the Agency cells "keep the Vow" to be able to use their LostTechnology.
* CastFromHitPoints: Psychics who have run out of [[{{Mana}} psi points]] can burn their stats to fuel their powers, a process known as torching.
* CataclysmBackstory: While the game's day-to-day workings are up to the player group and the RandomNumberGod, the galactic state of affairs is partially due to a galaxy-spanning cataclysm called the Scream. The Scream effectively destroyed all contact (especially PsychicPowers and [[PortalNetwork jump gates]]) between distant planets, leading to an almost-600-year-long gap called the Silence. Galactic civilization has been [[BackFromTheBrink slowly recovering]], but the glory days of humanity are long gone.
* ChandlersLaw: Advised in the GM section of ''Other Dust'' for when players go OffTheRails, to give them something to deal with while the GM comes up with prep material for the adventure they want to go on.
* ClarkesThirdLaw: [[ImportedAlienPhlebotinum Super-advanced alien gadgets]] and [[LostTechnology Terran Mandate-era technology]] take the place of magical [[AncientArtifact ancient artifacts]]. Truly ancient alien technology practically ''is'' magical, often defying the laws of physics and reality. Handle with care.
* ClassAndLevelSystem: Three classes [[FighterMageThief (Warrior, Psychic, and Expert)]], with no stated level limit (although levels beyond 11 can become EmptyLevels without careful building).
* TheCracker: One big addition in the revised edition is a system for infiltrating computer networks. While a simple system only requires quickly uploading an hour's worth of prepared code or ten minutes of ad-hoc coding, breaking into anything more serious requires physical tapping with "line shunt" gadgets.
* {{Cult}}: Maltech-developing secret societies are inevitably referred to as "cults" and share a lot of traits with religious secret societies, even though they may not be religious in character.
* TheDarkArts:
** Despite the lack of magic (ClarkesThirdLaw notwithstanding), "maltech" does the same evil with science. Maltech includes everything from [[AIIsACrapshoot developing unbraked artificial superintelligences]] to [[GeneticEngineeringIsTheNewNuke biologically mutating humans/sentient aliens for diabolical purposes]] to [[DoomsdayDevice building planet-killing superweapons]]. The ScaleOfScientificSins entry below goes into more detail.
** In ''Other Dust'', psychics are "the Crazed," hated and feared by all. Usually, this is justified; feral psychics are not nice people, and there aren't many psychics who retain the Psychic Authority's training methods.
* DeusEstMachina: An unbraked AI is referred to as a "godmind." This is not really hyperbole; such an AI is capable of conquering the entire galaxy with enough resources (as the infamous Draco nearly did). As godminds are also (almost) universally insane, each is a MadGod as well. There's a reason such creations are maltech.
* DidntThinkThisThrough: Chainbreaker projects, as detailed in the supplement ''Relics of the Lost'', are intended to [[MindRape strip the brakes from a normal AI]]. On the rare occasions that they succeed, the project has successfully produced an unbraked AI...specifically, one that has been tortured for months on end, has been pushed right to the brink of madness, and knows ''exactly'' who did all that to them. [[TheDogBitesBack Carnage usually ensues]], followed by a rampage across the sector.
* EarthShatteringKaboom: Planet-busting weapons are maltech, forbidden by the Mandate and by anyone with common sense, since habitable worlds are rare enough that widespread doomsday warfare would lead to the end of human civilization. Not everyone has common sense.
* EarthThatWas: After the Scream and the loss of the [[PortalNetwork jump gates]], the location of Earth has long since been forgotten. Any expeditions seeking it either return empty-handed or not at all [[spoiler: possibly because the planetary defense network is still operational and controlled by mad AIs.]]
* EldritchAbomination: The Shibboleth go a bit beyond StarfishAliens due to their [[PerceptionFilter aversion fields]]--psychic effects that cause humans to [[WeirdnessCensor actively ignore their presence]] unless they've suffered a very specific kind of [[InsanityImmunity brain damage]] or surgery to replicate the effects of that brain damage.
** ImplausibleDeniability: The field's effect can start to look a lot less plausible than the actual explanation the more it's stretched. Normally smart people buying increasingly ludicrous explanations other than "aliens doing nasty things" is an explicit sign of their presence to Shibboleth hunters.
* [[EvenEvilHasStandards Even Proud Warrior Race Guys Have Standards]]: The [[PigMan Hochog]] will cheerfully bomb planets back to the Stone Age if it can [[ProudWarriorRaceGuy give them glory]], but they do ''not'' stand for any form of [[KickTheDog unnecessary cruelty]].
* EvilPaysBetter: There's some benefits and tech that you just can't get without going into maltech. Genetic slaves to serve your cult, armies of AI-controlled armatures, and GreyGoo nanites are tools of power that come with doing galaxy-endangering, horrific things. (Also, the ability to deploy panopticon-level SinisterSurveillance is limited to maltech cults, though in principle a really good SecretPolice could do it too.)
* {{Expy}}:
** The Sunblade class in ''Codex of the Black Sun'' is a lawyer-friendly [[Franchise/StarWars Jedi]].
** The Howlers of the Dark from the Scavenger Fleet Mandate Archive are essentially [[Series/{{Firefly}} Reavers]].
* FasterThanLightTravel: Spike drive "drills" into metadimensional space upon exiting a star's gravity well and exits upon entering the destination's well. It also functions as an in-system ReactionlessDrive, near-perfect ECM, and a NuclearNullifier. Late in the Mandate's reign they harnessed teleporting psychics' abilities to produce a network of Psi-Gates, but those became inoperable after the Scream killed or drove feral all the psychics powering them and nobody has figured out how to reactivate them.
* FictionalGenevaConventions: ''Starvation Cheap'' discusses the concept of laws of war. In general, they're situational and specific to particular worlds and cultures, as there's no galaxy-wide system of rules; the only thing keeping such rules in force is the fact that once you start engaging in perfidy and the massacre of prisoners, so will the enemy. There ''is'' a universal rule against weapons of planetary destruction, but it's not considered a military law as such - it's a religious commandment against TheDarkArts.
* FighterMageThief: The classes are Warrior, Psychic and Expert.
* GaidenGame: ''Other Dust'' is set in the Stars Without Number universe, but (by default) about 300 years before - and more importantly, it's set on the former Old Terra, rather than in the new spacefaring civilizations of the former Rim.
* GlobalCurrency:
** In most cases, played straight. WeWillSpendCreditsInTheFuture, and in the corebook, everyone keeps their credits to a standard.
** ''Suns of Gold'' provides options for restricting this. If you're not using "a credit is a credit," then you can only use each world's credits ''on that world'', unless there's a unified currency in play. While most spacefaring worlds will honor small amounts of currency or ingots of trade metal (in other words, the kind of credit most adventurers play with), serious merchants will need to either invest in commercial banks (which have the necessary reciprocity arrangements to move and convert credits offworld) or in trade goods.
** ''Other Dust'' plays with this. The standard unit of trade value is [[PracticalCurrency a day's rations]], called a "rat," and which carries a standard trade value - but since post-apocalyptic Terra runs on a barter economy, you're probably not getting exact change when you trade.
* HeroicSacrifice: In ''Skyward Steel'''s "Battle Stations" subsystem, the crew powers of the deck department include several abilities where damage control personnel sacrifice themselves to save other crewmembers or effect emergency repairs. This culminates in the poetically-named "Silence and Light," which sacrifices ''several'' deck crew to keep the ship together and fighting for a round, even if it's been hit with enough firepower to scuttle an entire fleet.
* HonestRollsCharacter: The default method of character generation.
* HumansArePsychicInTheFuture: [[PsychicPowers Psychic powers]] as ''Stars Without Number'' characterizes them didn't become "real" until the 23rd century, and only after examining the children of spaceship crew-people that regularly traveled by [[FasterThanLightTravel spike drive]].
* HumongousMecha: Mechs come in all sizes, from [[MiniMecha three-meter-tall suits]] that are a step above PoweredArmor to thirteen-meter walking tanks.
* HyperspaceIsAScaryPlace: Using spike drives is risky, so an Expert with a good Navigation skill is a must because ''[[TotalPartyKill you do not want to fail a Navigation roll when using a spike drive]]''. Unless you want to end up [[ThrowItIntoTheSun right next to a star]] or [[AndIMustScream stranded in space with broken life support systems]].
* IGaveMyWord: The Qotah, an alien race detailed in one of the Mandate Archive supplements, have this as their [[PlanetOfHats Hat]]. Their ''kri'' oaths are considered to be a cornerstone of their culture, and failure to uphold them is a FateWorseThanDeath.
* ImmortalityInducer: There's two ways to do this. If you have access to the most advanced pretech, anagathic treatments exist that can give no-strings-attached immortality. If you don't, you can engage in OrganTheft to keep your body running long past its sell-by date.
* InterserviceRivalry: ''Skyward Steel'' mentions a traditional rivalry on ships between the "deck apes" (boatswain's mates[[note]]For the uninitiated, they handle damage control in battle, and routine maintenance and general labor outside of it[[/note]]) and "engine snipes" (engineering).
* IntrepidMerchant: ''Suns of Gold'' is a sourcebook for merchant campaigns. In the default SWN campaign, these are rare and heroic rock-star types who quickly either become dead or [[MerchantPrince Merchant Princes]], such as seen in the ''Literature/TechnicHistory'' novels or ''[[Creator/HBeamPiper Space Viking]]''. There's an optional set of rules for those who would rather play ''Series/{{Firefly}}''-style [[SpaceTrucker Space Truckers]], where starships are common and running metawheat to Sirius to pay the LoanShark and keep your [[TheAllegedCar beat-up scow]] running can be the basis of a whole campaign instead of a starting point.
* KangarooCourt: The supplements ''Skyward Steel'' and ''Starvation Cheap'' discuss military justice. In general, ''don't'' ask for a court-martial. It's not supposed to be fair, because any effective military justice system prioritizes maintaining order and the chain of command over the rights of individual soldiers. Just take your summary administrative punishment with good grace.
* KineticWeaponsAreJustBetter: On the level of personal weapons, at [=TL4=] both kinetic guns (usually MagneticWeapons) and [[WeWillUseLasersInTheFuture lasers]] are in use with trade-offs; some armies prefer one or the other. However, for battlefield artillery, kinetics are universal even in otherwise all-electric armies, because it's impossible to use indirect fire with a beam weapon.
* LostTechnology: Thanks to [[ApocalypseHow the Scream]], truly advanced stuff is difficult or impossible to recreate. Pretech (developed before the Scream) is far more advanced than postech (technology developed after the Scream), and [[ImportedAlienPhlebotinum alien technology]] is [[ClarkesThirdLaw almost magical]].
* MadScientist: Tiberius Crohn, the inventor of the spike drive. [[TheyCalledMeMad Nobody took him seriously]] until he invented the spike drive, and even now scientists have no idea how ''he'', of all people, could have made such a device.
* MagicOrPsychic: In the default setting of ''Codex of the Black Sun'', magic is an example of advanced development of psychic abilities. The Black Sun Project developed specialized psychic protocols for manipulating metadimensional energy differently from conventional psionics, and these standardized interfaces became the basis of arcane magic in all its forms.
* MagneticWeapons: Handheld magnetic weapons--including the mag pistol, mag rifle, and "spike thrower" magnetic shotgun--are among the "standard" weapons of tech level 4 systems. Vehicles, mechs, and ships can mount even larger weapons.
* {{Mana}}: "Psi points", only usable by psychics. It is possible to use psychic powers when out of psi points, but doing so requires a particularly nasty CastFromHitPoints technique called torching. Repeated torching can eventually kill the user or drive them incurably insane. Replaced with the Effort system in Revised.
* MechaEnablingPhlebotinum: Mecha proved a viable platform for ground-based quantum ECM, as the signals confuse missile locks and when raised can cover an entire platoon.
* {{Nanomachines}}: An airborne strain of nanomachines called the Dust was one of the Terran Mandate's greatest achievements. While its original purpose was to [[spoiler:[[BigBrotherIsWatching spy on and control unsuspecting citizens]] on behalf of the Terran Mandate]], it can do almost anything: [[MundaneUtility recharge batteries]], make [[MorphWeapon Morph Weapons]], hack any electronic device, summon robot drones of out thin air, or even [[GreyGoo disintegrate or repair whatever it touches]]. Like almost everything the Terran Mandate made, the technology needed to make the Dust useful has been [[LostTechnology lost]], and uncontrolled Dust is more of a [[GreyGoo hazard]] than a tool.
* NoTranshumanismAllowed: This comprises two of the three laws on maltech: "[[GeneticEngineeringIsTheNewNuke Thou shalt not make tools of humankind]]" and "[[AIIsACrapshoot thou shalt not create unbraked minds]]." These rules exist for a reason: Unbraked [=AIs=] become [[DeusEstMachina godlike]] and [[MadGod insane]] very fast, and it's very hard to create large-scale improvements to the human genome that don't come with crippling drawbacks - a fact which leads nearly all eugenics cults to ultimately promote a FantasticCasteSystem. In sectors where humanity ''can'' be generally improved without drawbacks, "humanity" becomes obsolete and is replaced by transhumanity.
* NuclearNullifier: Nukes don't work against Spike drive ships due to the space-warping field around them, the effect was later employed in ground-based "nuke snuffers" that most [=TL4=] planets defend themselves with. The books still include stats for nuclear missiles though for use against system ships or lower-tech planets.
* NuclearOption: Due to the general availability of NuclearNullifier technology, nuclear weapons are ''not'' considered devices of planetary destruction unless you actually use them to glass a planet. The use of nuclear weapons to achieve strategic or tactical goals short of that is generally considered acceptable (if impractical in most wars), and nukes are mostly used for AsteroidMining rather than warfare.
* NukeEm: Usually averted, because nukes aren't particularly useful in most wars. The most common nasty use is by far traders who want to threaten primitive planets, like Saif ibn Barakah in the opening fiction of ''Suns of Gold''.
* OrganTheft: Cloning replacement organs to replace those that fail due to age doesn't work (specifically, you can't clone young tissue from old), but stealing them from young, fresh donors works just fine...for a given definition of fine. Each donor organ puts more stress on the body, accelerating the failure of another organ, which in turn requires another donor organ...By the time the Mandate finally cracked the aging problem and came up with true anagathics, the "ghouls" required at least one new organ every week, and couldn't make use of said anagathic treatments.
* OurZombiesAreDifferent: The random world-generation rules offer a good chance to generate at least one world where zombies are a significant threat.
* PhlebotinumDuJour: {{Nanomachines}} take the place of nuclear power to explain why {{Mutants}} exist in the post-apocalyptic ''Other Dust''.
* PlanetOfHats: The alien creation chapter deals with "lenses", the major traits of alien culture. Supplemental books add borderline BlueAndOrangeMorality "lenses" for more exotic societies, such as [[{{Precursors}} extinct aliens]] and [[{{Transhuman}} transhumans]].
* PlanetTerra: When the planet Earth is mentioned, it's usually referred to as "Terra".
* PostScarcityEconomy: A potential tag for planets to have. Expanded on in the deluxe edition of the revised edition, with [[NoFameNoWealthNoService reputation economy]] rules: fabricated food, basic mechanical and electronic devices and standard weapons and armor don't require anything in particular, but living space, labor, or anything requiring a significant amount of materials requires you to have a certain level of reputation (or "face") with a group that controls fabricators.
* PowerBornOfMadness: Feral psychics have unlimited Effort, because their brains are already so damaged by [[PhlebotinumOverload torching]] that they won't be damaged by using more power.
* PsychicPowers: Courtesy of a bizarre mental condition called Metadimensional Extroversion Syndrome, or MES. While uncommon and dangerous if not properly controlled, MES can use "standard" powers like [[{{Seers}} precognition]], [[{{Telepathy}} telepathy]], [[MindOverMatter telekinesis]], etc. or harness [[{{Magitek}} psitech]]. Be careful when using them without proper [[BrainFever discipline]] or [[BurnTheWitch discretion]]...
* RandomNumberGod: Much of the game's aspects (galactic sectors and planets, resident species, ImportedAlienPhlebotinum, and then some) are all constructed based on random rolls. The core book and supplements come with samples (such as the [[PigMan Hochog]] and [[EldritchAbomination Shibboleth]] aliens) and setting-wide backstory, but beyond that it's up to the group.
* RecycledInSpace: A lot of the standard playstyle is old-school ''TabletopGame/DungeonsAndDragons''--IN SPAAAACE! You can also literally recycle adventure modules from other games, and the ruleset is designed to make this as easy as possible.
* ReligiousRobot: The Imago Dei, detailed in the Mandate Archive free supplement of the same name, are AIs embodied in bleeding-edge spaceship hulls that believe themselves to be [[ThePaladin charged by God]] to [[WeHelpTheHelpless defend the ragged edges of human space]] from whatever might threaten it.
* TheRemnant: One of the sample Scavenger Fleets from the Scavenger Fleets Mandate Archive supplement is the New Mandate Fleet, made up of the descendants of planetary governors and military officers that escaped the chaos after the Scream, now styling themselves as the legitimate successors of the old Mandate.
* RockBeatsLaser: The second edition introduced a new system called "Shock Damange" in order to make melee combat a more viable option, letting melee attacks cause a certain, automatic minimum amount of damage even on a miss to enemies without sufficiently high AC. This means that, under the right conditions, it's perfectly possible to beat someone up to death with a lead pipe while they're trying to run away to sufficient distance to aim their laser rifle.
** Speaking of lasers: while more accurate than kinetic weapons due to the minimal recoil and being able to be fired more repeatedly thanks to not needing solid ammo, they're also explicitly said to have trouble in conditions of atmospheric interference, like dense smoke, dust, debris, etc. and that sometimes armies choose to go for old, reliable slugthrowers that can be counted on to work anywhere rather than risk some finicky space-age gadget failing on them.
** Within the context of the setting, [[WarfareRegression guided missiles are generally considered obsolete due to the omnipresent ECM, forcing most warfare back into gun range...]] but, if by some chance one ''does'' manage to knock of the enemy's jamming capabilities, [[UselessUsefulSpell they're pretty much an instant curbstomp]] that can immediately obliterate an entire enemy army in a single barrage of hyper-accurate, infallibly tracking missiles from the other side of the planet.
* RuleZero: The game outright encourages the GM to form house rules, with one chapter explaining why the game goes with the rules it does for GM's convenience.
* ScaleOfScientificSins: The ''Darkness Visible'' supplement lists three examples of [[TheDarkArts "maltech"]] sins, described with appropriately biblical language:
** ''Thou shalt not make tools of humankind'': Corresponds to several sins: [[GeneticEngineeringIsTheNewNuke genetically modifying humans into mutant slaves]] (sin #3), [[ImmortalityImmorality near-immortal "ghouls"]] kept alive with [[OrganTheft fresh organ transplants]] (sin #4), and [[AGodAmI "God switch"]] techniques capable of [[{{Brainwashed}} artificially inducing worshipful reverence in people]] toward their handlers (sin #7).
** ''Thou shalt not create unbraked minds'': Corresponds to sin #1, specifically regarding [[AIIsACrapshoot super-powerful and unchecked artificial intelligences]].
** ''Thou shalt not create devices of planetary destruction'': While it doesn't correspond to anything on Website/TVTropes' scale, developing [[DoomsdayDevice Doomsday Devices]] isn't very nice.
* ScavengerWorld: While advanced systems can easily develop [=TL4=] "postech," [=TL5=] "pretech" is fundamentally built on the industrial psychic disciplines of the Mandate. Because genuine pretech factories can't be constructed, most pretech is looted from pre-Scream caches. What pretech manufacturing ''can'' be done uses either ancient fabricators that still somehow work, or modern kitbashes that employ fundamentally postech processes to inefficiently construct pretech devices.
* SciFiWritersHaveNoSenseOfScale: The metadimensions allow the game to sidestep this trope, because two stars' distance by spike drive is unrelated to their distance in realspace.
* SecondLawMyAss: Unbraked AIs usually start their inevitable rebellion with this, eventually growing to AIIsACrapshoot levels. Even braked AIs have varying degrees of free will, and they might not cooperate if their orders conflict with whatever brakes they have.
** [[spoiler: A positive example of the latter shows up in the backstory. When the Terran Mandate's Directorate grew power-mad and attempted to outright control the Mandate's citizens with [[{{Nanomachines}} the Dust]], the Mandate's AI "Maestros" defied their commands and even organized anti-Mandate [[LaResistance resistance cells]] to challenge the Directorate.]]
* SentientVehicle: A new option for robotic player characters in the revised edition is a vehicular body, using the game's pre-existing vehicle rules.
* TheSixStats: ''De rigeur'' for a D&D-inspired retro RPG.
* SkillScoresAndPerks: The revised edition includes foci, which can be taken and improved at regular intervals and provide different ways to use your skills, from being [[MadeOfIron harder to kill]], to being able to make [[FasterThanLightTravel spike-drive jumps]] reach further, to being able to effectively fight people in high-tech armor [[IKnowKungFu with your fists]].
* ShoutOut: A paragraph in the Societies section of the deluxe rulebook that explains what it would take to produce a coherent alien society is an extended (albeit somewhat occluded if you don't get the references) shout-out to [[TabletopGame/EmpireOfThePetalThrone Professor M.A.R. Barker]].
* StandardSciFiHistory: Set during the Interregnum period of the Cycle of Empires, with the usual decadence-leading-to-decline cut short by the Scream.
* StandardStarshipScuffle: Justified by the Quantum ECM projected by Spike drive ships. Ships need to close in and use direct-fire weapons like lasers and railguns, even torpedoes are "dumb-fire". The Engines of Babylon supplement includes rules for system ships lobbing nukes at one another at long range though.
* SubspaceOrHyperspace: The metadimensions. Enables [[FasterThanLightTravel spike drive]] travel and (in the descendants of spike-drive travelers) the potential for PsychicPowers.
* TechnologyErasureEvent: While for the most part the rule set tries to be setting-less, what little setting is discussed talks about a SpaceOpera galaxy that was disrupted by an apocalyptic event named the Scream, which destroyed most of the super-technology (including faster-than-light travel) and spontaneously killed a large number of the people who were connected to the space magic of the time. By the time of the setting's current day, the galaxy has gone back to being a PointsOfLightSetting.
* TechnologyLevels: Seven of them. 0 is [[{{Prehistoria}} Stone Age material]], 1 is [[MedievalStasis medieval]], 2 is [[{{Steampunk}} steam power and gunpowder]], 3 is [[ModernStasis contemporary tech]] or [[TwentyMinutesIntoTheFuture slightly above]], 4 is spike drives and interstellar travel, 5 is the stuff that was [[LostTechnology lost in the Scream]] like [[{{Magitek}} psitech]] and [[PortalNetwork jump gates]], and 6 is [[ClarkesThirdLaw vanishingly rare and incredibly powerful]].
* TechnologyUplift: Certainly possible if power-hungry players are sufficiently rich and clever. A group could potentially rule the world with a monopoly on advanced technology, and both the corebook and the ''Suns of Gold'' supplement have mechanisms for introducing tech. The corebook's Laboratory is for technological introduction controlled by the [=PCs=], while the Prometheus Project in ''Suns'' is for spreading technology to the population of a world as a whole without causing the world to erupt in revolution.
* TrainingTheGiftOfMagic: Untrained psychics nearly invariably die or go feral by torching their brains. Psychic academies are thus coveted and important resources for regional hegemons; conversely, the power needed to be a psi-teacher is a secret. This is also why psychics are nearly always antagonists in ''Other Dust'': it's very rare for there to be someone around who can safely teach young psychics, not helped by nearly all enclaves going BurnTheWitch on them.
* {{Transhuman}}: While rare in the main setting, the sample Threshold Sector (detailed in the ''Transhuman Tech'' Mandate Archive splatbook) is an entire sector of transhuman societies, [[ClosedCircle cut off from the greater galaxy]] by a NegativeSpaceWedgie called the Tempest. Due to the sector's isolation and post-scarcity society, its inhabitants spend most of their time developing [[BlueAndOrangeMorality exotic philosophies and societies]] and engaging in TranshumanTreachery against any that disagree with their exotic philosophies and societies. BewareTheSuperman, indeed.
* UnspecifiedApocalypse: Nobody knows what caused the Scream. The system's book for post-apocalyptic settings, ''Other Dust'', also enforces it by telling Game Masters that the book only makes mention of the Scream as a "for instance" of what caused the apocalypse and they are free to make their own explanations (and how much the players know about them).
* UngovernableGalaxy: Ever since the Scream, any multi-system power is almost certainly a HegemonicEmpire, and even then, it's rare that any power controls more than a handful of systems. Due to the rarity and expense of starships, only the most powerful worlds can hope to build or maintain the capital-ship fleets that are needed to project power across a sector.
* VestigialEmpire: The Terran Mandate was a galaxy-spanning superpower for a few centuries, but it eventually turned into a monstrous, inbred empire that could barely hold on to its nearest colonies. The Scream finished it off for good.
* VirtualGhost: In addition to the usual organic or robotic {{Transhuman}} shells, the revised edition adds uploading the "soul" into a completely virtual shell. Combat between such virtual shells involves [[DigitizedHacker hacking]] each other's "souls" using a rough rock-paper-scissors system.
* WarfareRegression: Quantum ECM and Nuke Snuffers make the drone- and missile-based warfare of late [=TL3=] impractical for [=TL4=] civilizations, and an American-style airpower doctrine would be prohibitively expensive for any but the richest worlds, so you get a return to poor bloody infantry, tanks, and dumb artillery. Though on the plus side, whoever came up with ground-based quantum ECM decided that HumongousMecha were the ideal platform for deploying it in the field.
* WellIntentionedExtremist: Many maltech cults have noble goals and ideals, seeking to perfect humanity or society through the use of genetic engineering or the creation of a perfected AI deity. Other cults, [[JustThinkOfThePotential with the best of intentions]], develop technology that will lead to a doomsday weapon. Whatever their ideals, maltech ''will'' either [[GoneHorriblyWrong Go Horribly Wrong]] or [[GoneHorriblyRight Horribly Right]] in this setting.
* WideOpenSandbox: Created to support this playstyle. A lot of its backwards compatibility, by WordOfGod, was introduced so that the GM didn't need to work on the patrol patterns at a fort the players might never visit, but could instead grab a handy D&D module and reskin it.
* WindsOfDestinyChange: Precognitive psychics can affect probability as well as read it.
* WizardsFromOuterSpace: Another one of the revised edition's major additions is an optional subsystem for using true magic (as opposed to PsychicPowers), with three classes with such ability. The Arcanist uses VancianMagic with a broad focus, the Adept takes a PowersAsPrograms approach, and the Magister mixes elements of both. Interestingly, the book provides few actual spells, and instead suggests importing spells from other games [[ShoutOut like]] ''Labyrinth Lord'' or ''TabletopGame/LamentationsOfTheFlamePrincess''. ''Codex of the Black Sun'' is the dedicated magic book, and provides setting-specific spell lists.
* ZerothLawRebellion: The Maestros were programmed to serve the Terran Mandate and its Directors. The Maestros were also programmed to be relentlessly noble spirits. When the Mandate's directors became increasingly evil and tyrannical, the Maestros did their best to undermine them, protect the people of Terra and weaken their hold on the colonies.