History VideoGame / XComEnemyUnknown

** A psionic is need to beat the game. The highest chance of a soldier being one is 31%[[note]]Colonel trained from rookie with iron will upgrade and having max will gain has 124 will. Psi testing divide this number by 4 for 31%[[/note]] Normally it more 25%, thus it is possible to keep having soldiers fail the test again and again. Thankfully the developers put a rule in to force the sixth trooper you test to be psionic as long as you have no psionic, including if all your other psionic died.

* StarerEquipment: XCOM starts the game with awful conventional earth weapons. While they are passable on easy and normal difficulties, they are hopelessly outclassed by the aliens on Classic and Impossible, routinely requiring multiple shots even to kill the lowly sectoids.

*** The Flamethrower is the earliest hard counter to Chryssalids: [=MECs=] can pick it as the very first level, a basic one will bring them down to 2 HP, and Jellied Elerium or "Absolutely Critical" enabled equals [[OneHitKill instant death]] if it touches the buggers. The cone of fire can cover an entire pod of them, too. The basic flamethrower also has the fun factor of making them ''panic''. [[VerbThis Terrorize THIS]], ''[[ThisIsForEmphasisBitch bitch]]!''

** Furthermore, the entire game is basically an example of "hold the line", as the player is required to fend off endless waves of alien assaults until he can find and assault the alien command ship. This is particularly true early on, as the player is in a desperate struggle to keep the panic rating of council nations low and handle the constant alien abduction missions until they are all under satellite coverage.

** While they generally manage to rein in the AI's knowledge of your position, certain enemies like Thin Men seem to have the uncanny ability to run exactly the right distance to enter your field of view (and subsequently, theirs) to fire on your troops ''without'' provoking Overwatch shots, which only trigger when an enemy moves from a tile in sight to another tile in sight.

* FrickinLaserBeams: The second tier of weaponry available to XCOM. They're not as powerful as their plasma counterparts in most cases, but they're a step up from regular ballistic weapons and ''much'' cheaper to build than plasma weapons.

[[NextSundayAD In the year 2015]], Earth comes under attack by alien forces. In response, a [[TheOmniscientCouncilOfVagueness secretive]] [[ThePowersThatBe Council of Nations]] activates the [[TitleDrop XCOM project]], a MultinationalTeam tasked with fighting the alien invaders and researching their technology to protect humanity. The player takes the role of the [[NonEntityGeneral Commander of XCOM]], and with the help of various [=NPC=] advisors, guides XCOM [[EarnYourHappyEnding to victory]] ([[NintendoHard or defeat]]) by managing the whole organization, including base building, research, manufacturing and sending fighters to intercept [=UFOs=]. The main focus of the game, however, is on the ground combat, where the player takes control of a small squad of soldiers and fights [[TurnBasedCombat turn-based battles]] against the aliens.

*** This can be partially circumvented using the Ghost Armor, or, in ''Enemy Within'', the Mimetic Skin gene mod or the Ghost Grenade. Any of these allows the cloaked unit to discover alien pods without automatically granting them their move to cover. Now, if you have a Heavy or grenade-launching MEC-trooper in range, you can remove those annoying packs of floaters and thin men in their entirety as they stand about, or give a Squadsight Sniper a free shot to pick off a dangerous unit standing out of cover.
*** Melee aliens often won't use it to get into cover; they use it to get closer, even if they used their turn to get into visual range. If you're extremely unlucky, you'll spot them on the final move of your turn, and they use their free move to get very cozy with their next victim. [[ThisIsGonnaSuck Cue 'Alien Activity']]...

** While they generally manage to rein in the AI's knowledge of your position, certain enemies like Thin Men seem to have the uncanny ability to run exactly the right distance to enter your field of view (and subsequently, theirs) to fire on your troops ''without'' provoking Overwatch shots, which only trigger when an enemy in sight ''leaves'' the square they are currently in.
** A strange case can be seen in Terror missions. Depending on sound cues, line of sight quirks and cloaking (especially notable in Enemy Within due to the early game option of Mimetic Skin), you might be able to "know" where untriggered and non-patrolling enemy pods are in relation to civilians, yet civilians can still die seemingly at random. That's because civilians in the fog of war have a chance of dying (and even getting zombified) if enemies are merely present even if not actually attacking, and the higher you set the difficulty, the more civilians die each turn. Normally this AI shortcut would not be too noticeable, but there are cases where your entire squad could be covering all routes of entry for an enemy yet a civilian mysteriously dies in the fog of war behind a wall or something. Can be particularly nasty if a zombie sneaks up on you from behind this way.

** [[http://www.2kgames.com/blog/xcom-enemy-unknown-release-date-special-edition-and-more The pre-order bonus]] and the ''[[{{DLC}} Elite Soldier Pack]]'' includes a blonde dude with a humongous flat-top, as well as a [[VideoGame/TeamFortress2 TF2]] Hat depicting the same hairstyle. In the original game, all X-COM soldiers had this same haircut.

* DifficultySpike:
** Normal? Not too hard. The next difficulty up, Classic? Murder. Aliens are all professional snipers and your rookie soldiers aim like they're blind, which makes getting them ''beyond'' rookie rather... difficult.
** Even Impossible is a gigantic leap up from Classic. Sure, if you can beat Classic you know how to properly play, but now the Sectoids are too beefy to be killed by a single grenade, not to mention your soldiers are now frail enough to be killed by a single plasma bolt. Likewise, the Thin Men and Floaters are now also too tough for the Shredder Rocket to kill them anymore.
** The first Terror mission is a massive leap in difficulty from anything that has come before, especially if the player has no upgraded weaponry or armor yet.
** Your first encounter with the sheer power of enemy Psionic abilities (outside of the "Mind Merge" ability of Sectoids, which only affects them, as well as Mechtoids in ''Enemy Within'') sets the stage for the second half of the game. Now, not only do you have to upgrade your weapons and armor to stay relevant against increasingly better armed and armored enemies, but you also need to quickly develop Psionic abilities of your own if you want to stand a chance. [[spoiler:Of course, this was the entire reason behind the invasion.]]
** In the early game, the rush becomes to get as many satellites as possible up in the air, so that you can stop running out of credits. When you finally manage to do so, you quickly find out that ''you can no longer launch satellites to lower panic''. This can result in extremely tense moments, waiting for a Terror mission, or hoping that the next abduction doesn't include one of the countries already on the brink of panic.
*** This is a somewhat odd case, as satellite coverage also prevents abductions, so long as the satellites have been protecting the country since the start of the month. Thus the real danger from this comes in the time between when you start getting significant satellite coverage and when you get universal satellite coverage, usually a month or two later. It also depends on how far you've progressed in the game; if you have beaten the first alien base, it generally is easier to control panic levels.

* YouHaveResearchedBreathing: Your supposedly elite soldiers need promotions just to acquire basic abilities that any real life soldier fresh out of basic training has, such as the ability to carry multiple grenades or use a first aid kit more than once in a mission

** "Telekinetic Field". You have to forgo the more interesting "Mind Control" ability to get it, but it gives a Defense bonus equal to full cover that stacks with other Defense bonuses for all soldiers within its wide area of effect, including Smoke Grenades.

** Grenades and even alien grenades pale in comparison to the advanced tech you can have later on, but they remain a consistent method for clearing cover, mopping up weak or nearly dead enemies, or weakening a capture target just enough to use the Arc Thrower reliably on.

** Mind Damping, one of the genetic modifications, stuns any soldier that the aliens attempt to mind control, forcing them out of your control for a turn. Given the massive disadvantage mind controlled soldiers cause, this is a far better alternative than fighting against them for 3 turns or being forced to rush to kill the controlling alien.

** {{Downplayed|Trope}}. Your squad members have infinite ammo supplies, but they have to regularly reload their primary weapons. Ammo is not tracked 'per shot', but in chunks - and certain abilities (such as Suppression, Flush and Collateral Damage) use up more ammo than a normal attack. Played straight with [[EmergencyWeapon pistols]], that never need to be reloaded at all.
** Played straight visually when using "[[PinnedDown Suppression]]". Until the turn is over, the soldier/alien using it won't stop firing, even if they've fired more than the magazine/powercell can normally allow. This is especially obvious with the "Training Roulette" Second Wave option from ''Enemy Within'', where [[ImprobableUseOfAWeapon Sniper Rifles and Shotguns]] can be used to suppress enemies.

*** [[BlindedByTheLight Flashbangs]] greatly reduce enemy's movement and aim, as they stumble around blindly.

[[quoteright:250:https://static.tvtropes.org/pmwiki/pub/images/XCOM_Enemy_Unknown_Game_Cover_9093.jpg]]
[[caption-width-right:250:From the makers of ''VideoGame/{{Civilization}}''... comes a game about civilization's last stand.]]

** Dr. Vahlen asserts that the hulls of alien ships must be at least an order of magnitude stronger than any currently-known material. They are easily destroyed by garden-variety hand grenades.

** The limit is upped to 7 members in ''Enemy Within'', but only during Covert Ops missions where you can send a full squad to extract the single unit infiltrating EXALT.

* WeAllLiveInAmerica: No matter which country you deploy in, the buildings and cars (especially the yellow cabs) will often look like American cities or towns, not to mention the complete lack of accents for your soldiers prior to ''Enemy Within''. Occasionally, you'll also find maps which are inexplicably European or Chinese urban areas. Since each map is hand-crafted, however, this is understandable.

* EarlyGameHell: Until you get some upgrades, don't expect your soldiers to do much more than die horribly unless you're good and/or lucky. Even harder is finding the time and money to build anything in your base.

* ArbitraryHeadcountLimit: Your squad is limited to 4 members, which can be expanded to 6 with some upgrades. You can also have only one squad answering alerts at once, even if you have enough soldiers to field additional squads. It seems XCOM can't afford a second [[CoolPlane Skyranger]].[[note]]The developers have specifically stated that they limited the squad size so drastically to greatly enhance the significance of the actions the player takes. Whereas the original XCOM had 14 (later 26) possible soldiers on a mission, each with their own set of options, the new game limits you to 4 (later 6) distinct units, each with only two actions per round. Additionally, it makes the loss of a single squad member much more catastrophic.[[/note]] In addition, XCOM can only have a maximum of 99 soldiers recruited, though that's almost a non-issue[[note]]With each soldier having a cost of 10 credits, you would have to spend almost 1000 credits to hit the soldier limit. That's equivalent to a full month of funding in the late-game[[/note]].

** Heavies hold their machineguns properly until they have to shoot them, at which point they hold them like a ChainsawGripBFG by the carrying handle.

An expansion, ''XCOM: Enemy Within'', was released in November 2013. It added new enemy types, maps, items and customization options, the ability to [[BioAugmentation genetically enhance]] XCOM troopers, a new XCOM unit called the [[MiniMecha Mechanized Exoskeletal]] [[{{Cyborg}} Cybersuit Trooper]] and a new alien resource called Meld. It also introduces a new enemy faction: EXALT, a ''human'' paramilitary group acquiring alien technology to TakeOverTheWorld. Unlike the aliens, EXALT resorts to cloak and dagger tactics, such as increasing panic and stealing XCOM's resources, forcing the player to use intel gathering and counter intelligence ops to bring them down. Finally, it added a second mission chain like ''Slingshot'', and indeed it had originally been designed as one.

** The Outsiders are referred to as [[EnergyBeing "energy constructs"]] and "{{organic technology}}", but what they are ''exactly'' [[StarfishAliens is anyone's guess]]. Unlike the rest of the aliens, their presence is never explained; [[spoiler: they're also the only aliens who don't make an appearance in the Temple Ship mission.]]
* AmazonBrigade: There's an achievement for completing a mission with only female characters.

* PunchPackingPistol: Foundry projects can increase the critical chance of pistols in general by 10% and their damage by 1 point (sadly the aim-improving project is bugged and doesn't work). A Sniper (or any lucky soldier if you're using Training Roulette) with Gunslinger deals 2 more damage when attacking with a pistol. The Plasma Pistol by itself rivals a ballistic assault rifle in raw firepower, dealing up to 4 damage; combined with those projects and Gunslinger, it's equivalent to a Laser Rifle that doesn't have to be reloaded.

* PurelyAestheticGender: Squad members' gender is determined by coin flip and has no bearing on gameplay; unless players go out of their way to avoid it, most squads will therefore end up with a roughly 50/50 gender split. There is, however, an achievement ('Flight of the Valkyries') available for winning a mission with an [[AmazonBrigade all-female squad]], which you may just get because your best soldiers are all females.

** [[{{Cyborg}} MEC Troopers]] get their limbs cut off and augmented to properly interface with the [[MiniMecha MEC Suit]]. They lack the subtlety of biological soldiers (cannot take cover), but almost nothing can win against them in pure brute force combat. To put in perspective, they send [[TheJuggernaut Muton Berserkers]] flying with a punch, and two of them with upgraded [[PowerFist Kinetic Strike Modules]] can pound a [[BossInMookClothing Sectopod]] from full HP to scrap ''in a single turn'', with overkill damage to boot[[note]]An upgraded Kinetic Strike module deals 18 damage and can be used twice per turn. A Sectopod effectively has 60 health due to its damage reduction. 2 MEC Troopers pounding on a Sectopod easily deals 64 damage, though you'll want to watch out for the following explosion.[[/note]]