UFO Alien Invasion

UFO: Alien Invasion is a Quake II engine-based open source freeware strategy game that is effectively a direct remake of X-COM, though it adds several new mechanics, changes up many of the old ones, and adds a completely new (and really rather good) story. The current release version as of this writing is 2.5, released in late Jule 2014.


 * Abnormal Ammo - Encased Plasma and Antimatter ammunition with much greater lethality and different type - EP goes through armor easily, while Antimatter gives great deal of blast (less efficient against good armor) damage without radius  of destruction like normal explosives do.
 * Absurdly Sharp Blade - The alien Kerrblade is a dissection tool, while the human-made monomolecular blades are merely terrifyingly sharp and made a little like Katana. Both go through flesh like it's butter and Kevlar like it's paper, and generally One-Hit Kill unarmored (or even armored) targets. The Kerrblade does slightly more damage, but as it's not a purpose-built weapon it's rather bulky and unwieldy. The monomolecular blade doesn't do quite as much damage, but attacks faster, weighs less, and is small enough to be carried in a holster, thus making it a viable backup weapon that effectively obsoletes the standard Combat Knife.
 * Alien Autopsy - Performing one allows you to see that species' stats.
 * Alien Blood - Played straight with Orthoks which have green blood, but averted with Tamans which have red. The robotic bloodspiders expectedly drip black grease instead.
 * Alien Invasion - You read the title, right?
 * Antimatter - Played with: Humans can barely make a few molecules at a time with the comtempory tech, while the aliens seem to be able to fill weapon magazines and spacecraft fuel cans with grams of it.
 * Area 51 - Before v 2.5 the icon for building UFO Yardin external installations list was stylised "51"
 * Artificial Stupidity
 * Some aliens allow themselves to hide in places where grenades can be dropped on them. Also, while they consider a weapon's spread and usually avoid friendly fire, cooking oneself or a teammate with a bounced plasma grenade is still common. At least, they got patched out of stupidities that led them to waste the only grenade on a lone civilian when there are armed opponents.
 * And while they are at it, they often bunch up together allowing a single soldier to kill a number of them in a single turn, especially if you have explosive weapons or flamethrowers. Aliens also doesn't know how to pick up items from the ground, and if they run out of reloads, they will just stupidly walk around like an idiot unless they have a melee weapon.
 * Civilians still oddly behave like those in X-Com. They don't try to take cover, get in your way during the crossfire. They now run from aliens that are attacking them, though.
 * Most jarring during the mission where you need to protect military convoy. None of the soldiers are armed and they just run around.
 * Aliens are still not smart enough to storm your base properly (they will just wander around at the entrance instead of going in for the kill).
 * They also spend a lot of time trying to shoot you through solid objects like walls and their own crashed ships. It gets taken Up to Eleven when they first try to shoot you through a wall, and only after that walk a few steps into a better firing position. As in, one where your soldiers can shoot them with ease on your turn.
 * BFG - Heavy weapons are a separete category and, generally speaking, they all are good enough to be worth lugging around.
 * Subverted with the Electromagnetic Rifle, which is huge and bulky because it has to be in order to work properly, not because it is ludicrously powerful. It's only marginally more lethal than the standard sniper rifle, same has range, but is heavier to carry and slower to use. Its advantages are great precision and penetration (only Coilgun goes through stuff easier) and alien armor being  less resistant to heavy projectiles. However, later you can develop (in v2.5) antimatter-enhanced shells for it that hit as hard as HE rocket, but without splash damage, and still can punch through walls - that's when the  fun starts.
 * Brainwashed and Crazy -
 * Break Out the Museum Piece: Played with. All of the base designs, battle tactics, strategy, and organization are copied right out of the old PHALANX manuals and documents. However all the old equipment is replaced with the latest in 2084 technology.
 * Combat Exclusive Healing - Medikits can only be used in battle, but are capable of healing wounds in a single turn which would require days of hospital time to recover from.
 * Construct Additional Pylons - Not strictly unavoidable, but... there's no need to cover the whole planet in highly developed bases just to have radars and aircraft at hand, then chase down every UFO with interceptors that, after all, have limited range and high costs to risk. There are separate radar towers and missile batteries. Aliens eventually will notice radar signatures and launches and attack such places, but when it's not a base, it's trivial to replace. And the more decoys you got, the less likely they'd to choose a base as the target.
 * However, you still need to build more bases due to Cap of 3 external installations per base. Specifically, per working Command Center, which requires Power Plant - and at this point you can just throw in a Radar (it's better than on towers). Then you may want to add a Hangar with interceptor. Cost of Living Quarters + Storage for the pilot and ammo is negligible... but if you have these, could as well add a few mediocre soldiers with equipment, for some security in case of a raid.
 * Cool but Impractical: Rocket launcher is useful only if you plan to use it for very long-range shots, and even then it's not precise enough to be practical (long-range shots are needed at all only if an alien immediately threatens civilians). Heavy laser or particle beam rifle can be researched early on, both got second best range with better accuracy and no splash damage, same for laser rifle with even better accuracy (but less damage). For everything else, grenade launcher, while rather short-ranged, is more versatile, less dangerous to friendlies and has much greater rate of fire, dealing more damage per time.
 * Curb Stomp Battle: In story the first few attempts to battle the aliens resulted in this... And we were the ones getting stomped. The first battle the soldiers didn't even know what they were fighting before they got wiped out.
 * Damage Typing: As easily seen in armor stats, not all types of attacks are equally efficient against everything. And there are stun weapons. Data shows that total number is 25, though.
 * Death of a Thousand Cuts - If you're not careful, your combat teams will suffer this during periods of heavy alien activity - during particularly hectic periods there can be five or six missions every day, and with no time for your troops to rest and recuperate between missions, all the little wounds add up surprisingly quickly.
 * Dummied Out - Flashbangs, smoke grenades, and all incendiary weapons (minus the flamethrower) have disappeared from the human arsenal for a while due to bugs; 2.4 brings them back.
 * Earthshattering Kaboom: Well not earth shattering but if the Antimatter Storage ever loses containment, kiss your base and a good dozen miles around it goodbye.
 * Elite Mooks - Your forces are humanity's Elite Mooks, the best and brightest soldiers culled from the elite elements of every nation's militaries and law enforcement agencies.
 * Emotion Bomb - Only if you are doing very badly, your soldiers may go berserk and attack each other. This also applies for the enemy that a wave of suppressive fire sometimes make aliens turn on each other.
 * Note that there's also a small chance low-morale troops will go berserk and take out their rage on the enemy, which usually turns out just as badly for you, because it generally results in them charging blindly into enemy fire. It's quite Badass if they survive, though.
 * It's also possible for friendly or hostile soldiers to freeze up completely if their morale is low, cowering uselessly behind the nearest piece of cover.
 * Energy Weapon - The somewhat Halo-esque looking plasma series of alien weapons.
 * Charged Attack: "Unrestricted Blast" of Cannon Particle Accelerator and "Ball" of Plasma Blaster allow powerful single shots with reduced damage/ammo efficiency.
 * Frickin' Laser Beams - Played about as accurately as man-portable lasers can be - they are extremely accurate, has good effective range , but have mediocre damage compared to other precise weapons and VERY low stopping power, and their beams can be scattered by smoke, fire and dust.
 * Ditto for Particle Beam, except it is substantially more powerful, but slightly less accurate and subject to same penalty to fire and smoke.
 * Flechette Storm - Shotguns with flechettes are very lethal, especially close up when all 8 will hit. Before v2.5 riot shotgun had full auto mode. Also, when you finally meet aliens in armor surviving 2-3 shots, you can see their armor is worth researching.
 * Grenade Launcher - You really need at least one in the team it's more practical indirect attack than hand grenades. Also, often it's the only way to finish an enemy before their turn: grenades fly over a building now, but soldiers take time to run around it. With flechette ammo it works as a shotgun - not good, but better than nothing when storming a cramped place and grenades are useless, while flechettes make it one more weapon with reaction fire. Incendiary mostly sucks, but isn't completely useless.
 * Grid Inventory - Another carryover from the X-COM series, complete with the accompanying Inventory Management Puzzle.
 * Guns Akimbo, Dual-Wielding, or Sword and Gun - Can be done with some accuracy penalty. You can also dual wield a 2 handed weapon with a handgun, but you cannot fire the 2 handed weapon without the other hand free. Even if you only use pistols though, you still only able to fire the weapons one at a time. The only advantage of wielding 2 weapons is that you don't have to pull out the other weapon from your holster when you need it, which cost some TU (just think of the advantage of having a handgun in 1 hand and a kerrblade or stun rod on the other). Many aliens with plasma pistols do the same.
 * Hollywood Tactics - There's nothing stopping you from playing this way in theory, but it's a good way to get a lot of your troops needlessly killed.
 * Imperial Stormtrooper Marksmanship Academy - Fortunately, it isn't quite at X-COM levels, and even the worst recruits can at least hit what they're aiming at occasionally. That said, both your troops and the aliens can be wildly inaccurate at times, even at point-blank ranges. Crouching before firing largely negates this issue, though . Also, full-auto mode tend to drown in bullets even armored targets.
 * Infinity Plus One Gun - The Coilgun in 2.3, though you need to obtain an alien needler in order to get it. In 2.5 it's inconclusive, especially because new enhanced ammo improves existing heavy weapons, though Coilgun and Electromagnetic Rifle stay on top due to precision.
 * Instant Home Delivery - You can sell equipment at one base and immediately buy it back at another for the same price. What makes this especially egregious is the fact that there's also a "Transfer" option that allows you to send equipment between bases, but this generally takes a few days, whereas selling-and-rebuying happens instantly. New recruits (Scientists, Workers, and in recent build Pilots too, not just soldiers) are delivered instantly as well.
 * Karl Marx Hates Your Guts - As of v.2.5 you can produce anything available on market, but making an item costs exactly as much as buying the same. It would make some sense if making an item and paying the workers was comparable, but it's not the case, so you either fire workers, suffer losses while they do nothing, or find something non-trivial to do. After some time, other parties begin producing th stuff you can build, too.
 * Speaking of Marxism, the only result of production of non-exclusive items is... eliminating deficites, and before 2.5 the reserve of most items (even grenades) on market is ridiculously low (the whole Earth's supplies of many items are below X-Com Apocalypse levels!). Thus, if you burn some ammunition faster than it can be supplied, or want to keep more reserves, an idling workshop suddenly becomes useful. Equipping everyone with Flashbang and Smoke grenades (which despite their weakness often give the only way to save civilians) takes most of the supply, so it's an obvious choice.
 * Kill It with Fire - Flamethrowers are deadly against most aliens since their armors, while good against bullets can barely protect them from the flames. It is also one of the two starting weapons, the other being Grenade Launcher, that continue to be useful until the end. The only weaknesses are limited range, heavy weight (which precludes weaker soldiers from using it without a heavy speed penalty), and its rather bulky ammunition.
 * Kinetic Weapons Are Just Better - Played with. Although bullets are quite good against unprotected alien flesh, and flechettes are even better, alien armor does a disturbingly good job protecting its wearer against gunpowder-accelerated projectiles, and as such by the mid-game the vast majority of the standard human arsenal will be obsolete. The grenade launcher and the flamethrower remain useful for the entire game, as the former can be adapted to fire a cartridge version of the alien plasma grenades and the latter is a cheap way to light things on fire, but they aren't technically firearms.
 * Leeroy Jenkins - Some alien crafts appear to behave this way in recent builds, charging blindly towards vastly superior enemy forces rather than running away.
 * Magnetic Weapons - The Bolter rifle, the alien Needler, and the Coilgun from the v2.3 release.
 * Misapplied Phlebotinum: Mostly averts, and continues in that direction. v2.5 allows to make ammunition based on alien antimatter containment technology - results are... impressive.
 * Mohs Scale of Sci Fi Hardness - Pretty high up as far as military sci-fi goes. The game's built-in UFOpaedia articles have fairly lengthy explanations of the tech, and the technology includes everything from antimatter engines and buckyball-infused armor to accurately-portrayed lasers and caseless ballistic weapons.
 * More Dakka
 * The human grenade launcher had burst fire setting before v2.5. Also, the plasma blaster is powerful and rapid-fire, but has terrible accuracy, putting it squarely under this trope.
 * The Needler is pretty much the epitome of this. Instead of normal sniper weapon which fire single powerful slugs, this one actually go the other way around by spamming hundreds of small needles instead.
 * The human machine gun is, obviously, rather good at this, making it an extremely useful suppression weapon in the early to mid game. Its range and stated damage equals to assault rifle, but long bursts are quite lethal. 20 bullets at e.g. 5% to hit give 64% total; scoring more than one hit becomes more likely - which is good, since even unarmored Tamans very often survive one bullet.
 * Multinational Team - The game's code even tracks them by nationality, although there's no indicator of country of origin in the interface yet.
 * Obvious Beta: Justified because, well, it's still a beta. Remember, save early, save often!
 * Oddly Small Organization: Even if you're doing exceptionally well, PHALANX will rarely have over a hundred combat-ready soldiers, with 40 or fewer troopers being the typical amount. You'll usually have a far larger number of scientists, workers, support staff, administrative personnel and pilots, but the organization is still extremely small considering its area of responsibility is literally the entire planet.
 * Oh Crap: Ignoring the amount of times this happens to you while playing, reading the research letters has the Chief Science Officer having a lot of these. The most notable example is where they are taking a UFO apart and find that it's powered by antimatter and they only found this out after opening up the fuel tank.
 * Also several times he will also realized just how technologically advanced they are compared to us.
 * Pistol-Whipping - Proper melee weapons will do a better job, but it's possible. Thrown equipment does tiny damage, and Stun Rod allows "Bludgeon" attack for normal damage instead of stun.
 * Randomly Generated Levels/Cut and Paste Environments/ - Most of the battle maps tend to rely on pre-rendered sections of terrain being put together in different combinations, just like the original X-COM games.
 * Relationship Values - For each of the multinational power blocs funding your organization. Their happiness with you influences the amount of money you receive and the number and quality of recruits you're given - a nation that barely tolerates you will give you barely any money, and either very crappy troops or no troops at all, while a nation that loves you will shower you in money and give you the best and brightest men they can find.
 * RPG Elements - Your soldiers have a series of stats and skills that improve with use.
 * Save Scumming: Not a completely straight example since saving and loading isn't allowed in battle. However you can hit the reset mission button as many times as you like.
 * Sci-Fi Writers Have No Sense of Scale - The original story for UFO:AI had the aliens invade earth on their mothership, housing it's entire population (several trillion alliens). In order for the mothership to contain, let alone sustain, those numbers, the ship would have to be larger than Jupiter.
 * Averted later with the Antimatter specs. The Chief Science Officer says at one point about current antimatter production on Earth "That may sound like a lot Commander but it would take us 80 million years to make a gram of antimatter at the current rates."
 * Scripting Language: Lua-based scripting.
 * Secondary Fire: attack modes are as important as in X-Com series, and there are more variety.
 * Short-Range Long-Range Weapon - The sniper rifle from earlier build appears to be unusually inaccurate even if it is used in what is normally Assault Rifle range. Fixed in newer build. Laser weapons are exact opposite as even the pistols are deadly accurate at long range, but they don't do much damage to compensate it.
 * Short-Range Shotgun - Largely averted. The riot shotgun has decent range - if not necessarily great stopping power at maximum range - with flechette shells, and can alternately be loaded with slug rounds that got even better range. The micro shotgun sidearm and flechette shots for grenade launcher are more to this, though.
 * Shown Their Work: All over the place. It helps that anything wrong will quickly be pointed out in the forums.
 * Shout-Out - The Plasma Pistol looks a LOT like plasma rifle from Halo.
 * Spiritual Successor - To X-COM, of which it is basically a Fan Remake - the weapon progression is similar, too - and somewhat to the UFO: After Blank games.
 * Standard FPS Guns - This is not an FPS game, but the weapons appear to have this idea, one for each family of weapons. It's actually justified in-story - a program called 'Excalibur' was instituted that selected a range of different weapons from throughout the world in various different classes, collecting the best weapons humanity has to offer and providing them to your troops in a standardized form.
 * Standard Status Effects - What the flashbang does, the aliens don't have them since they don't care about stunning or collateral damage anyway.
 * Of course, they'd do a lot better if they did - the flashbang is arguably one of the most useful tools in the human arsenal, and skilled deployment of them makes virtually any mission a cakewalk.
 * Static Stun Gun - The electrolaser, though it may kill by accident.
 * Take Cover - An integral part of any strategy more complex than 'Throw corpses at the enemy until they run out of bullets'. There are also a number of tactics for defeating enemy cover, such as explosives that can be bounced around/arced over it and Electromagnetic Rifles/Coilguns, which can shoot straight through walls.
 * Techno Babble - Surprisingly, the fluff text for the game is pretty well written.
 * The Greys - Following all the X-Com series, most likely the first alien you will encounter is a slightly ugly humanoid, though this time they are in jumpsuits.
 * The Virus
 * Universal Ammunition - The DF cartridge used by all laser weapons - pistol eats 1 charge, rifle 2, heavy laser 3 (4 in burst mode) per shot; the electrolaser got its own variation, though.
 * Video Game Flamethrowers Suck - Averted. The flamethrower is one of the best close-quarters weapons in the game, remaining useful in a room-clearing role well into the late game, and is more useful than other incendiary weapons.
 * Wave Motion Gun - Particle Beam Cannon, especially the ship version. To lesser extent, heavy lasers.
 * Wave Motion Tuning Fork - Plasma weapons appear to work on this principle based on their shapes, but reading the in-game UFOpaedia entries on them reveals that the plasma itself is actually generated internally, and the 'tuning fork' assembly is actually a pair of spinnerets which generate a thin film of an advanced plastic-like material to (briefly) contain the plasma, thus forming it into a projectile.
 * We Have Reserves - It is possible to play like this, but unlike in X-COM, this strategy is strongly discouraged in this game due to the limited number of recruits available per month (especially on harder difficulty) and the bad starting stats of new recruits. You have to train them and keep them alive.
 * With This Herring - At last, averted. Not only you immediately get weapons both quite lethal (until aliens start wearing good armor, at least) and convenient enough to give everyone, but also armor decent enough to make One-Hit Kill with the weakest of alien weapons very unlikely... Oh, and you can build useful installations other than bases. Recruiting still can be a problem, though - as in, on medium difficulty when you'll build the second laboratory, there won't be enough of scientists to quite fill it.