We're gonna take a wild guess here and say it mightbeaboutaliens.
In May 2004, humans achieved alien contact. Or rather, aliens, named Reticulans, came to Earth. Ignoring all attempts to make contact, the aliens unleashed a massive cloud of spores that completely covered the skies. One week later, the spores, having rapidly multiplied, fell en masse to the surface, choking the life out of the planet. The few survivors of the devastation gathered together with one purpose in mind: revenge.Thus begins the story of UFO: Aftermath, the first game in the UFO: After Blank series by Altar Interactive (officially, it's known as the "UFO" series, but you know the Internet). Considered the Spiritual Successor to the X-COM series, the UFO: After Blank games combine a geoscape-like view of the planet for strategic planning, and tactical squad-based action for missions. Research and development are extremely important for advancement. In many respects, the game is similar to X-COM, but the addition of real-time tactical missions, as well as a unique strategic game focused more on territory than resources and a complex story, sets the game apart from X-COM. Unfortunately, the series does not break from the X-COM tradition of crippling bugs and glitches. This got worse with the sequels, which were often rendered unwinnable.UFO: Aftermath was followed up by the sequel UFO: Aftershock, which actually continues from the bad ending of the previous game. The sequel then produced a sequel/simultaneous-quel of its own, UFO: Afterlight, set on Mars as brave colonists attempt to terraform the planet into a new Earth while defending against a multitude of aggressors.Despite the bugs, the games are probably the most dignified competitors for the title of "Spiritual Successor to X-COM", with Afterlight being often praised for approaching X-COM's level of complexity and depth. Note, however, that compared to other strategy games, all three are Nintendo Hard, at least during the first stages.The whole trilogy can be bought on Steam or without DRM from GOG.com.
After the End: Aftermath begins roughly one year after 70-80% of the life on the planet was killed by the alien bioweapon.
Alien Autopsy: Alien corpses can be studied to determine the weaknesses and vulnerabilities of their species.
Alien Invasion: Well, yes. Noteworthy for a halfway plausible reason for to make the aliens defeatable, namely that they're a doomsday cult on the run from a benevolent alien empire; they used a stolen ship and fled through the gateway to Earth (blowing it up in the process) in an unprecedented act of insubordonation. As such, they are limited to what they could make off with. In fact, their master plan is in part to put themselves in a position of strength before the authorities can crawl back to Earth at sub-light speeds and install a new portal into the solar system. Their plan was to cover the Earth with a giant mutagenic organism that would become sentient and near-godlike when it covered the whole planet; they intended to use this organism, the Biomass, to gain the upper hand against their pursuers, if they could control it. At least that's what they thought they were doing.
Aftershock takes place 50 after humanity had made peace with the Reticulans and given them control of the Earth. In-game, due to a first-unknown catastrophe, the Reticulans are in a feral, animal-like state, while the human refugees from an orbiting space-station (built as part of the peace treaty) try to take back the Earth. All of a sudden, an object shows up at the edge of the Solar System, and you get an ominous timer counting down to the imminent invasion. This new race, The Wargots, are on a sort of religious pilgrimage/crusade to Earth, and ally with a bunch of human cultist nutjobs down on Earth. Later, a second, similar starship shows up, carrying a third race called the Starghosts to Earth, who proceed to attempt to sterilize the planet.
After a lot of research, you get to the bottom of the riddle: the "starships" used by the Wargots and Starghosts are actually gigantic asteroid-like interstellar organisms that use their enormous psychic powers to enslave entire civilizations and use them to fight in a cosmic-scale mating ritual. The Wargots and Starghosts came here in a male "Myrmecol" (like the ant-colony plants on Earth), while the Reticulans had a female with them. The female made the Reticulans cover Earth in Biomass, and when it was complete, in "screamed" across the entire universe, bringing the males to Earth to compete for the female. That "scream" was what drove the Reticulans planet-side insane, crippled the ones on Mars, and gave the humans psychic powers and cyber-compatible mutations.
Afterlight and Aftershock have those Reticulan authorities show up. In Afterlight you can either kick their heads in or work with them; either way, that portal is not still getting built within the context of the game, and if you kick their heads in, maybe not at all.
Also, in Afterlight, the Beastmen look like they were invading at first, using Martian hyperspace portals, while the "Martians" are waking up from stasis because the humans tripped over their defense robots. It turns out that The Beastmen are the original Mars residents; the "Martians" actually came to Mars in a male Myrmecol many millennia before, defeated the Beastmen, and banished to some far-off hellhole using the portals. The Beastmen are now coming back, to brutally reclaim their old home.
Applied Phlebotinum: inverted - in Afterlight, the humans' Mars base has a super-advanced alien transport ship that runs on fossil fuels. The characters do wonder about the reason Mars has fossil fuels, but go along with it. They have things to do. It's the first of many indications that something else is at work.
Armor-Piercing Attack: Some conventional weapons have Armor Piercing ammunition. The Warp Weapons take this to the extreme, since they are able to completely phase through armor, and in fact do more damage the heavier the armor the target is wearing.
Art Shift: The artwork and character design became increasingly cartoonish as the series progressed.
Awesome, but Impractical: Heavy Power Armor in Aftermath. Provides a lot of protection and allows you to use powerful heavy-armor-only weapons, but limits you to a walking speed, and generally is only available after the Reticulans introduce Warp weapons, which cause more damage if the target is wearing more armor. Heavy Armor has a Warp weapon protection level of 0%, and warp weapons almost never miss.
Base on Wheels: The Laputa in Aftershock, which overlaps with Flying Fortress.
Boom, Headshot: Level 3 Sniper Training in Aftershock will let your snipers target the torso, arms, legs, or head of humanoids. The latter has... predictable effects when combined with an M82;
Boomer critically hit Morelman (14193 damage)
Boring, but Practical: Regular assault rifles and sniper rifles can serve you very well for the first half of Aftermath and remain viable weapons for fast troops later on, especially once your troops get their rifles/marksmanship up high enough. Even the basic Remington sniper rifle can take down most transgenants and Reticulans quickly at long range, at least until you encounter Deathbellows.
Can't Catch Up: If soldiers can't catch up literally (low speed ratings), they often wind up showing up at firefights too late to kill anything and thus can't catch up figuratively (no kills means no leveling up).
Simply participating in a mission does give a small amount of XP in Aftershock and Afterlight. In fact, depending on specialization, you might not want a soldier to have a high agility rating (snipers, for example, have incredibly long ranges, and don't need to get into a firefight in the first place).
Charles Atlas Superpower: Without the HWPs and high casualty rates of X-COM, this tends to happen to every soldier you command as long as their Speed and Capacity ratings aren't already more than two levels behind the squad maximum.
Cool, but Inefficient: The ZVI OP Falcon sniper rifle, a clunky-looking gun with shotgun power at rifle ranges, a two-bullet magazine, and enough time between shots and/or reloads for a Reticulan to fuck up your vantage point with an incendiary rocket.
Laser weaponry in Aftermathsounds good; Frickin' Laser Beams with a very high rate of fire. But its low single-shot damage output tends to let the enemy return fire before they're killed so you'll generally reach for the plasma and gatlings instead.
Afterlight tends to avert this: instead of using old-model bullet weapons, you only have a pistol, rifle, sniper, and shotgun model for projectile weapons. After the incredible amount of choices available in Aftershock, this seems like a step back, until you realize that those four models are really all you need (barring laser/plasma/explosive weaponry, of course).
Copy Protection: Physical copies of Aftershock are protected by StarForce, known for its malware-esque modus operandi. Thankfully, every legitimate digital version (and obviously, most of the illegitimate ones) has shaken this off.
Cue the Sun: Used in the intro for Aftershock, just when the Laputa refugees find the second Laputa.
Deflector Shields: Some Reticulan Armor Suits have shields. You can also manufacture shield generators and install them onto armor suits in Aftershock.
Game Breaking Bugs: If commentary on the Let's Play thereof is to be believed, Aftershock is chock full of these. Known horror stories include saved games corrupted across an entire game profile, destruction of system files, and the uninstallation of anything running in the background, including Steam (currently the best way to get the After Blank games legally). (The Goons seem to applaud Aftershock for getting rid of one user's iTunes processes, though.)
The underbarrel grenade/plasma launcher attachments corrupt save data in Aftershock
If you're too aggressive against the Cult and wipe out all of their bases before researching their collaboration with the Wargots, you'll never be able to proceed past that point. Speaking of which, if you hold off on researching vital techs, you can quite handily prepare yourself for major upcoming events... though that might be good for for some.
This particular bug has been "fixed". If you wipe out the last Cult stronghold before they're supposed to be wiped out, they'll randomly reappear on three base provinces. Any three base provinces. Including yours.
Aftermath has a very nasty one, because you might not even know it's a bug, frantically looking for the solution. Namely, after biomass is introduced, you need to take sample of it and put it into research and in no time you can repell it. If the bug kicks in, you can't take the sample. Never. Meaning you will take all those extra-hard missions in infested locations for nothing, watching in despair as more and more of Earth is covered, finally taking all your bases down.
Determinator: Humanity's hat in this universe. Every other race in the galaxy is more advanced, or more numerous, or simply more powerful, but humanity wins out every time because they justwon'tgiveup.
It certainly helps that humanity has the remarkable ability to make use of any new technology in a disturbingly short time. The best advice the aliens could have used would have been to outfit their weapons with self-destruct mechanisms. As it is, they can expect any new-to-humans technology they field to be used against them in as long as two weeks and as short as six hours.
Somebody at Firaxis Games read this article; in XCOM: Enemy Unknown (the actual reboot to the game that UFO: After Blank was a spiritual sequel to), the invading Sectoids do fit their technology with self-destruct devices that go off when the user flatlines. Of course, they didn't think to trigger it when the user falls unconscious, which leads to hilarity ensuing.
Eldritch Abomination: The Myrmecols are ancient, star-faring beings so powerful that they can mind-control entire planets on a regular basis, while the inhabitants don't even notice.
Arguably, the Starghosts. These bizarre aliens are extremely psychic, so much so that the " Starghosts" you fight are actually armies of hypnotized animals being led by a single projected illusion of the actual sentient alien. A projection that can kill you, from the other side of the Solar System, no less.
Encyclopedia Exposita: Each game has a very detailed "Glossary" that details everything from autopsies, to weapons and new scientific principles. Aftermath had by far the most detailed (and, one might even say realistic) descriptions.
Perhaps one of the best descriptions in the glossary in Aftermath is for Reticulan lasers. "You put your hand here, and pull the trigger here, and the laser is emitted here." In a text-only description.
If you finish Aftermath without accepting the Reticulan Offer, you are told that the liquid that the aliens used to create Biomass was not related to their other technologies. It's only made clear what they meant in the next game.
In Afterlight, after you conduct a study on the material you use as "Fuel", Ramirez comes to the conclusion that it's the result of Biomass putrefaction, indicating that the "Martians" covered Mars in Biomass long ago, like the Reticulans did to Earth. The Solar System is just unlucky like that.
Genre Savvy: One of the main reasons the Reticulans are able to do so much damage against humanity is that they're extremely aware of their own limitations. As such, the first step of their invasion plan involves bombarding military installations into dust from orbit, and the second step consists of a mass bombardment of the entire planet with biological weapons and then waiting a year. Only then do they send in ground troops.
Geo Effects: Aside from the obvious ones of LOS and cover in a tactical game for all of the series, Afterlight's missions have an environmental hostility rating. If one (or all!) of your team member's suit can't handle that level, the suit will break and the wearer will take continous damage until they fall unconcious and eventually die.
Also has the possibility of making the game much harder than it should be if you're not careful. If you don't start terraforming by the third week, environmental hostility ratings will go higher than any suit you have at that point, preventing you from running missions safely (and endangering your severely limited troops).
Justified. Most of the race died, anyone still around is probaly an Action Survivor.
Immune to Bullets: Aftershock's Flatsters, which are large, dinner-plate sized crustacean-looking things. They're extremely weak to energy weapons, but essentially immune to non armor piercing bullets, and still highly resistant to those. Fortunately they're little more than an irritation due to their exceptionally weak melee attack and hideously inaccurate ranged attack.
Starghosts appear as psychic projections that can only be disrupted by psi and energy attacks.
Implacable Man: The Wargot Powered Armor in Aftershock, which can take a ton of damage in one sitting. Even after being knocked unconscious, they can take plenty of punishment before going down. Compare them to Terror From the Deep's Lobstermen.
Perhaps the best example of this is the Wargot weapons in Aftershock. After researching them, you can make your own plasma weapons, but the description of their plasma launcher indicates that it requires pulling two triggers that are not comfortable for humans to use simultaneously. So scientists rig all captured Wargot weapons with special devices so that humans only have to pull one trigger.
The only time that you really can't reverse-engineer a weapon is the time when you receive an aid package from Earth in Afterlight, which contains a pair of megaton-overpowered Warp Cannons. It's stated that the Mars base doesn't have the equipment or resources for that kind of weaponry. Two of them suffice, though, since they're levels of magnitude above anything the other guys have.
Beastman equipment (with the exception of their weapons) can't be reverse engineered. Their medkits are based on an entirely different physiology, and their detection equipment is only good for detecting non-Beastmen. However, studying their detection equipment does allow you to develop methods of defeating it.
Infinity Plus One Gun: Several for Aftermath. The best is probably the Enhanced Plasma Rifle, which will drop most Reticulans in one shot. Other examples include the H&K CAWS shotgun, with over 1000 damage in burst mode, and the M240 flamethrower, which clears rooms in moments. Afterlight, strangely, doesn't have Infinity Plus One Guns despite the presence of huge gatling cannons; the best overall weapons you get in the game are the basic rifles you develop early, but they are upgradeable.
In the early game in Afterlight, lasers fall by the wayside to rifles. In the late game, laser cannon can rule the world; Martians and Beastmen Matriarchs are very weak to them, and very resistant to projectiles.
M82a Barrett .50 calibre sniper rifles, and the katanna when fighting Wargots, are close enough in Aftershock.
In-Universe Game Clock: X-COM's infamous Geoscape returns, albeit with less versatile settings (10 minutes or 1 or 6 hours per second in Aftermath).
It's a Wonderful Failure: Bordering on nightmare fuel, the game over cinematic from Afterlight is nothing short of a tearjerker, as the expedition leader limps to watch his beloved colony go up in flames, hear his friends dying over the comms, and he himself run out of oxygen all at the same time. As he dies, the entire colony explodes and he is engulfed in the shockwave, and everything goes dark.
Katanas Are Just Better: For absolutely no logical reason whatsoever, it's a melee weapon in Aftershock. The insane cultists like to charge at you with them, often not wearing any armour. In this case, katanas do not stop bullets. Not even slightly. Pipes and combat knives are available for more practical-minded troopers.
In the right hands, Katanas are just better. A level 3 Ranger with Superhuman agility will move insanely fast to close to combat distance, and with sufficient strength (generally Very Good or better), they can kill almost anything in seconds.
Katanas return in Afterlight, and at first it's difficult to see why: When you first get the opportunity to use katanas, every enemy you encounter is either equally damaged by other weapons (Reticulans and projectile weapons, Beastmen and laser weapons), resistant to slashing damage (Beastmen, Robots), or both, and even the faster soldier is still going to take time to close the distance to their target, during which they will get injured. Then the Martians enter the fray, with their extremely high dodge rating and resistance to everything but incendiary weapons...and slashing weapons. In fact, the human scientists specifically recommend using the katana For Massive Damage, and create an entirely new buzzsaw to take advantage of this crippling weakness.
Kill It with Fire: It's a pretty regular recurrence in the series that the most powerful enemies have a weakness to fire. The Plecton Transgenant, which is an acid-spitting tripodal mutant from the early stages of Aftermath, is very weak against incendiaries, as is the Chrysalis, a psionic floating worm that can paralyze your entire squad and leave it at the mercy of other enemies. In Afterlight, the same goes for the Beastmen's Rollers, which are dog-sized balls of death that are nigh-indestructible with your early arsenal (except for maybe the Warp Cannons, which are dreadfully inaccurate) and like to roll up behind your squaddies and sprout 2-meter-long spikes that kill them painfully.
Mars: Afterlight's setting. Of course, by the end of the game, it's not.
Mecha-Mooks: A staple of Afterlight's "Martians", though you shouldn't really call the Mechs and Spider-Mechs "mook" to their face. Notably, though, you can make your own Mecha Mooks, and with the small number of people on your team and the possibility of blundering into something very lethal, you may have to rely on them. Fortunately, they can rise from the depths of Mookdom to incredible heights of Bad Ass: be the first on your block star system to own a heavily-armored quadgatling gun-/rocket launcher-/laser cannon-/Annihilator- toting death machine. Just don't use them as an alternative to a human pointman; they don't react fast enough to get off a first shot, and Lightning Guns or Plasma weapons will fuck them up hard.
Also a mid/late game option in Aftershock. There are three flavours, and all are useful for spotting, scouting hazardous areas, and generally drawing enemy fire away from your less-expendable troops.
The Wargots have one, called the Wargot Scout, which are effectively cannon fodder for your troops.
More Dakka: The collapsible weapons, enormous gyro-stabilized turreted weapon platforms that can only be carried and used by soldiers wearing Powered Armor. The first one you're likely to come across, the Collapsible 4-Barrel Machinegun, spews out lead at a blistering 37.5 rounds per second in the general direction you're pointing it. They only get more powerful and Dakka-riffic from there.
Afterlight's quad heavy weapon drone turrets.
Mix-and-Match Critters: Several types of Transgenant basically consist of alien chunks grafted onto human corpses.
Multiple Endings: Aftermath is one of the rare cases where the "bad" ending is canon. The Council of Earth gives up the fight against the Reticulans (which one might argue they were winning) and surrenders the planet to them, while in exchange the aliens build a giant space station in orbit to house the Council, and a base on Mars, with 10.000 frozen colonists and a few scientists, as an vanguard to the terraformation of the red planet.
In Aftermath, because of the biological weapons the Reticulans used, many Earth lifeforms had been transformed into horrific monsters. These "transgenants" ranged from mutated animals and humans to creatures that could easily be Starfish Aliens.
As well as the transgenants from Aftermath, Aftershock introduces two factions of humans that had developed special abilities from certain mutations caused by the Biomass. The first faction, the Cyborgs, are able to graft cybernetic implants onto themselves without any problems. The other faction, the Psionics, developed potent psychic abilities.
Obvious Beta: Played way too straight in Aftershock- on top of all the aforementioned Game Breaking Bugs and shoddy copy protection, its own uninstaller is nonfunctional and an important research item doesn't appear until you give the savegame a nudge in the hex editor or send it to the company to fix it. And since the company has been out of business for about four years or so (and is Czech at that)...
Organic Technology: Inverts the curve set by X-COM, as organic armor and weaponry becomes less common as the series progresses. Reticulans are so advanced that almost everything they build is a living organism, much like The Edenists. Of particular note is their ships: they start with a Reticulan "volunteer", inject them with something, and the ship grows from and around the new pilot, who is conscious. There's no one flying Reticulan UF Os because the UF Osare the pilots. Human scientists wisely decide not to copy the tech directly.
The technology becomes scarce only because there are fewer Reticulans to build and maintain (feed?) it. It's still vastly more efficient than any other race's weapons. You can have a heavily-armored 7-man Gatling-equipped army fighting for you, but when one Reticulan uses his mind-control projector to make them kill one another, or his brain-exploding psychic missiles, or spacetime-twisting Warp devices to turn your squad into paste, you realize who's really in charge of the Galaxy.
Out of the Inferno: Between the M240s and the incendiary alien rockets in Aftermath, both sides are unfortunately going to pull this. (Though it is a rare Reticulan indeed who will be able to waltz through an M240 blast.) Your enemies will continue doing so on up to and through Afterlight...mainly because you are the only one with flame-based weapons by then.
Plant Aliens: The Martians in Afterlight are Little Green Men in the most literal sense: they're plant-like, photosynthetic humanoids. Like plants, they are very difficult to kill with bullets; you need edged weapons to take them down. And again, like real plants, they are very sensitive to electromagnetic fields (which is how they communicate), which explains why their technology is based around computers and robotics, while their weapons are plasma cannons, lightning guns and EMP grenades.
Powered Armor: The Wargots in Aftershock, and to a lesser extent, the Cyborgs.
Also averted in Afterlight where the game actually handles men and women as different 'subraces' internally. Female characters have lower base strength and carry capacity than males, but on the other hand they have higher intuition and slightly smaller body size which makes them harder to hit.
Psychic Powers: The Reticulans in Aftermath are terrifyingly powerful in the late-game because of this. Psychic Projectors allow mind control of your soldiers, and even the best kind of protection can't make them immune. Of course, once you begin training your own psychics, the tables rapidly turn. One high-grade Psychic and a spotter are all you need to kill a dozen Retties without firing a single bullet.
Mind Control weapons are absent in Aftershock, but show up again in Afterlight. The Reticulan Expedition loves them, and use the one-psychic-army strategy to great effect. There's also a device that allows you (or the Martians) to hack and control robots, in a similar manner.
The aptly named Psionics in Aftershock, who are a faction of human women that possess psychic powers because of a mutation developed at birth. Because the trait for these powers is fatal to males for some reason, there are only female Psionics.
There's also the Starghosts, strange aliens that appear lategame in Aftershock that use intensely powerful psionic powers, and look pretty damn creepy as well. If you fail to defend a province from a Starghost attack, they'll deploy a mind control device that will conquer the entire country, and you can never recolonize them.
Power Copying: Humanity does this in terms of technology. If an enemy fields a weapon against the humans and they manage to capture it they will figure out how to operate it themselves, likely within the span of a day or less.
Then they take this a step further by actually taking the basic idea of the weapon and improving upon it. Aftermath has several good examples such as the Plasma Rifles which are utterly devastating at nearly all ranges. The Gray's mean while only have access to comparatively weak grenade launcher weapons.
Warp weapons have an even better example. Reticulans mostly use pistol and rifle model warp based guns. Humans take the technology and make what's describe as a warpgatling gun!
Rare Guns: All sorts of stock and not-so-stock Hollywood firearms can be looted as you expand or built by your people. As you'll learn, most of them aren't much help.
Aftermath delights in throwing all kinds of weapons at you, though to its credit, you'll generally find rare weapons in the countries where they were developed (the Neostead shotgun is generally found in the southern areas of Africa, for example). By the time you get some of them, though, you're likely using laser or plasma weapons, making them impractical.
Aftershock lets you build all sorts of projectile weapons. In the assault rifle category, you can make the AK47, HK33, M4 and XM8. However, unless you're looking to do a lot of damage (AK47), the XM8 is superior due to very high innate accuracy. Most other projectile weapon categories end up functioning the same way.
Afterlight gracefully sidesteps the mess created by excessive weapon types: its real weapons are just as detailed, but since the game's set (a) in a scientific outpost, and (b) ON MARS, the base only has enough guns for half a squad. It has to manufacture everything else by itself.
Scary Dogmatic Aliens: The Reticulans came to Earth to conduct an experiment of epic proportions, and locals be damned.
Their buddies back home aren't better. While not exactly a Hive Mind, their sense of unity and loyalty toward their own kind is so strong, that the dissidents who flew away on the Myrmecol are hunted down as an unprecedented abomination.
Secondary Fire: There's the standard single shot/burst modes for most guns, and extra fire modes can be added by attachments in Aftershock. Options include underbarrel shotguns, plasmaguns, grenade launchers and single-shot dartguns, for all your quiettakedownneeds.
Sequel Difficulty Spike: In Aftermath, you're almost literally thrown new recruits every week, and you'll likely have a hard time running out. In Aftershock, you have to pay for new recruits, and the better your relation with a particular faction, the better (and more expensive) the recruit, but you're never likely to run out of meat for the grinder. In Afterlight, you start with 12 potential soldiers. After about a month and a half, you get one extra soldier, and two weeks later, you get two more. In addition, 8 of those original 12 soldiers are also scientists and technicians. You'd better get used to protecting your people and quick.
Shout-Out: The Reticulan's Biomass that they planned to use to turn the whole planet into a massive, nigh-godlike supercomputer with awesome psionic powers is all to similar to the Xenofungus from Sid Meier'sAlphaCentauri.
There are also power cells called Energons in Aftershock.
Sorting Algorithm of Evil: The Reticulans or rather, the rebellious Reticulans are the first aliens humans encounter, and they succeed in wiping out 80% of humanity. They're the least powerful of humanity's enemies in the series.
Sorting Algorithm of Weapon Effectiveness: Mostly averted, except in Aftermath. Although there are always obscenely powerful weapons, most enemies have varying degrees of resistance to certain types of weaponry (projectile, energy, explosive, plasma, etc). And, as much as you might like outfitting all your soldiers with plasma spewing death blasters, you have to make all your weapons and ammo, and generally speaking, the ammo for advanced weaponry either has a higher cost or a longer production time, meaning you'll want to hang on to those old-fashioned projectile weapons even up to the endgame.
Starfish Aliens: While most of the sentient aliens are some sort of humanoid biped, there are some weird variations. The Martians are plant-like, the Beastmen look like an unholy cross between a gorilla and a praying mantis, the Starghosts aren't even shown, but appear as ghostly psionic projections, and the Myrmecols are enormous Eldritch Abominations that at first sight look a lot like asteroids.
The alien's "pets", on the other hand, are positively bizarre: the Reticulans' Transgenants are hideous mutants made from human corpses and/or animals, the Beastmen's Rollers and Spiders are spike-sprouting footballs and dog-like insectoids respectively, and the Starghosts' battle-beasts don't even look like living beings.
Hybrid/parasite/etc. type Transgenant lifeforms are more of an "oops", an example of why exposing things to Reticulan Biotech without being very careful is a bad idea. The Biomass itself has it's own defensive systems that are even more "starfish" like. The Muckstar especially - a spiked ball that attacks with an electrical discharge. In Aftermath, it rolls along on spikes rising out of the Biomass. Why? Nobody really knows. In Aftershock, the Muckstars have adapted to float around on their own (seeing as most of the Biomass is gone) using gas-filled compartments.
Starfish Language: While most aliens' languages have some sort of vocal component (Reticulans use both sounds and telepathy), the Martians' "spoken" language is extremely hard to decipher (being a complex interface of individual Martians' electromagnetic fields), and the process is portrayed rather realistically: first you raid a ruined underground city for their scientific records (which mostly consist of empirical facts about the universe and mathematics), then you learn how to write their language, and only after that can you nab one of them and communicate with him to learn their "spoken" version. After doing this, you can begin peace talks with them.
It depends, the flamethrower hits harder than anything other than a Warp Demolition Device, BUT you really need to micromanage that weapon. Its range is quite short, and worst of all its wall of flame effect can spill backwards. So it's quite easy to set yourself and any team-mates around you on fire.
Villain Decay: The Reticulans themselves. In the first game, they're extremely deadly due to their advanced technology, incredibly effective shields, and use of explosive weapons. In the second game, they're reduced to cannon fodder. In the third game, they're reasonably deadly, but even your basic armor protects against their laser weapons, and their psionic attacks are relatively weak (unless they get lucky with a critical mind control, which is relatively rare), and they're cripplingly weak to projectile weapons, which are among the first weapons you get, so they're still easy to kill. Then the OTHER Reticulans show up, and you remember that the ones you've been fighting have been operating on a shoestring of supplies for more than 50 years. The Expeditionary Force is better armed, better equipped, highly dangerous, and immediately offers an opportunity for peace with you specifically BECAUSE they could easily kick your ass: the game would be almost impossible if you were forced to fight them the instant they show up.
Wave Motion Gun: Warp weaponry is the peak of Reticulan engineering. It uses a method the humans can barely comprehend to tear targets up by warping the space said targets occupy. As such, the Reticulans make them into Rifles and Pistols. The Humans, on the other hand, make Resonators and Demolition Devices, and then later, Warp Medkits.
Interestingly, the Warp weapons work on the principle of crushing inorganic objects to injure people. This introduces a crippling weakness to the weapons: targets that don't wear armor. No armor provides a startlingly effective 90% resistance to Warp weapons. Of course, given the fact that not every Reticulan in a mission will carry Warp weapons, it's a brave soldier (or a stupid one) that doesn't wear armor against them. Or a scout.
The Alien Microslug Accelerator is the single most horrifyingly powerful gun in the Reticulan Arsenal. If you see one, it's very likely that it's already been fired. If it's been fired... might as well start the mission over.
The Collapsible Plasma Gun is more powerful per-se (single-shotting any Green Alien Armor), but the fact that it takes long to deploy and that aliens use them for offense rather than defense really cuts down their effectiveness.
Afterlight has the Warp Cannons, shipped straight from Earth via express-spaceship in please-handle-with-care-and-don't-disassemble cases, and the Annihilator plasma beam weapon; the plasma supposedly has antimatter in it.
Worthy Opponent: What the Reticulans eventually come to regard the humans as in Aftermath, to the point that they actually offer humanity an opportunity to surrender instead of annihilating them. Canonically, humanity accepts.
The Reticulans even base one of their late-game weapons designs, the Collapsible Plasma Gun, on human portable turret designs. The Glossary description for the weapon remarks on the irony.