* AnticlimaxBoss: The Alien Brain at the tail end of ''UFO Defense''. See the page for examples of just how ''pitiful'' the final fight can get.
** The Cthulhu {{expy}} at the of ''Terror From the Deep''. It's an EldritchAbomination, and it can't hurt you. It doesn't even have strong enemies protecting it like the Alien Brain did.
* AuthorsSavingThrow: After the [[InternetBackdraft not-so positive reaction]] to the FPS reboot, finally announcing and focusing their marketing much more heavily on a strategy game that's faithful to the original style by Firaxis Games (with many of the staff that worked on the originals at Microprose in the dev team) seems to be this. It helps that the FPS was delayed into ''2013'', and it was {{Retcon}}ned to be set in the past of the XCOM universe, derailing its status as a ContinuityReboot.
* AwesomeMusic
** [[http://www.youtube.com/watch?v=WOdRt_c8nfY dogfight]], [[http://www.youtube.com/watch?v=QiBPb1u56tk the intro music]], [[http://www.youtube.com/watch?v=m5TfPAe2Z78 the geoscape theme]], [[http://www.youtube.com/watch?v=DKlirm7th-k the briefing theme]]...
** Like many fan remakes, ''Cydonia's Fall'' may or may not see a day of release, but at least they made a nice [[http://lorcan.freelanzer.com/ Remix OST]]. Here's a [[http://www.youtube.com/watch?v=AeoLXJYKUdA sample]].
** While less awesome, the ''Terror from the Deep'' music is just as atmospheric with the [[http://www.youtube.com/watch?v=Im6a7v7QgSs Geoscape]] [[http://www.youtube.com/watch?v=_lOVLY5UbQ4 themes]] (here's [[http://www.youtube.com/watch?v=437gc1Ho8kw some]] [[http://www.youtube.com/watch?v=i8kDDq_0QfA arrangements]]), [[http://www.youtube.com/watch?v=WiEbNi-7Gpg Interception themes]], [[http://www.youtube.com/watch?v=CPLVS-RSeGk Briefing themes]], [[http://www.youtube.com/watch?v=EiVUXCp8_jo Battlescape themes]] and [[http://www.youtube.com/watch?v=VTPJfvD8vFo De-Briefing themes]].
** Apocalypse has an awesome combat theme, aptly named [[http://www.youtube.com/watch?v=Miho2Db2wWM Kill them ALL]] (slightly [[http://www.youtube.com/watch?v=WAfGGRQi-6k longer]] version).
** ''VideoGame/{{Civilization}} II'' had a track named ''[[http://www.youtube.com/watch?v=hO7hySC6H9o X-COM]]'' (later renamed to ''They're Here''), which is basically a remix of the menu theme.
** Most of the remakes themes, in particular the combat music.
* BrokenBase: ''2K Marin's XCOM'', either you thought it had a shot at being worthy of the name ''X-COM'', or you didn't. There was no middle ground. Notably slanted in the direction of the "didn'ts".
* ComplacentGamingSyndrome: Admirably, ''X-COM'' is balanced to a degree which undermines this. Late-game enemies such as Sectopods have a built-in resistance to plasma weapons, which throws your entire arsenal out of whack if you've sold off your laser weaponry. The baseline tactic of priming a smoke grenade on Turn 1, throwing it, and deployment on Turn 2 is not a cure-all; The Skyranger might deposit you directly in front of a Muton, priming his own grenade in anticipation, so you had better scout around. You might think yourself clever for waiting out the clock and letting the aliens come to you. But at least when the aliens are huddled in the UFO, you know ''where'' to find them; if you wait until Turn 20, they will file out of the UFO and fan across the battlescape, increasing the chance of a surprise ambush. There is no sure-fire, winning strategy.
* ContestedSequel & FirstInstallmentWins: While the first game regularly tops (or is at least present in) various "best game" lists, opinions on the sequels are another matter entirely. Outside of die-hard fans, many aren't aware that sequels existed in the first place.
** ''Terror from the Deep'': [[NintendoHard Challenging]] upgrade to the original game with an awesome Lovecraft-esque atmosphere and a few forgivable bugs, or samey, buggy MissionPackSequel?
** ''Apocalypse'': A superior update to the formula with an excellent real-time combat mechanic, or an unfinished wreck with terrible graphics?
** ''Interceptor'': Fun space-sim-lite that kept most of the series' intrinsic mechanics, or a rather terrible attempt to cross genres?
** ''Enforcer'': ... Actually, most people agree this one was terrible, though you will occasionally see people mentioning that it's not so bad if you A) forget it's supposed to be part of the X-Com series and B) are in the mood for an arcade-ish shooter.
** As for the commercial and freeware X-Com clones... bring an asbestos suit.
** For Enemy Unknown, you either think it's been dumbed down to the point of being unrecognizable as X-COM, or modernized in an effective and enjoyable way that can be appreciated by new audiences and old fans alike.
* DemonicSpiders
** In the early game, candidates abound:
*** Chryssalids. They have as many as ''80'' or more Action Points/Time Units on the hardest difficulty (able to go from off-screen to melee attacking in one turn), and as little as 60 on the lowest. To move one tile takes 4, or 6 if diagonal. Thus, they can blitz your troops from alleyways and corners. On top of that, if your surprised agents kill the Zombies created by a Chryssalid with reaction fire, out pops a ''new'' Chryssalid.... with FULL TIME UNITS and ready to make more Zombies out of your men. Chain reactions of frightened soldiers killing zombies with Reaction Fire before getting zombified by the freshly hatched Chryssalids are the number one cause of {{Total Party Kill}}s when battling against Snakemen.
*** Ethereals (champions of psi-spamming) deserve special mention as frustrating and unfair enemies.
*** Later in the game, this is reversed and a strong squad is virtually invincible, not in the least because ''you'' are the one making with the psi-spamming at that point.
** ''Terror From the Deep'', however, brings them back in force:
*** Tentaculats take it to a whole new level with their ability to ''fly'' when underwater. Combine this with the fact they ''love'' to hide in little nooks and crannies (which exist in alien bases for this sole purpose, it seems), one Tentaculat can ''decimate'' an ill-prepared attack force single-handedly. One particular problem with these monsters is that they only show up on alien base attacks, which means the first time you go to an alien base, you're in for a surprise. And lest you think that you can ignore the alien base and therefore the tentaculats, leaving a base active will decrease your funding score and increase the chance of nearby countries signing alien pacts. You're screwed either way.
*** Bio-Drones: Don't you just love enemies that upon being shot, immediately spin around and return fire with 100% accuracy?
*** The Lobstermen, who are basically supercharged Mutons with ridiculous resistance to almost all forms of weapons. Only the Drill are guaranteed to kill them fast.
** ''Apocalypse'' is no slouch here, either.
*** [[ActionBomb Poppers]] are tiny annoying self-propelled bombs that close the distance to your troops in an unfairly short amount of time. If you're playing in turn-based mode, pray harder for reaction fire as they approach.
*** [[BrainwashedAndCrazy Psimorphs]] take ''forever'' to find, an eternity to kill and all this while easily wreaking havoc upon the fragile minds of your agents. Oh, and they can also fly.
*** Do you remember the tanks from the previous games? This time the aliens have them. Capturing a live [[MoreDakka Megaspawn]] and not losing half your force in the process is quite possibly the single most challenging task in the game.
*** Anthropods and [[EliteMook Skeletoids]] are comparatively benign compared to the above examples, until they start carrying advanced equipment like [[InvisibilityCloak cloaking fields]] and [[TheNudifier Entropy guns]] around just to make sure that you never catch a break.
*** Last but not least, there are [[FaceFullOfAlienWingWong Brainsuckers]], coming to turn your agents against you and there's not a bloody thing you can do about it (unless you're playing in real-time mode, in which case they are much less of a threat). Unlike Chryssalids, they [[OhCrap can also jump]].
* GameBreaker: [[{{Gamebreaker/XCOM}} There's a sub-page for this]].
* GoodBadBugs: Most every release and patch of ''UFO Defense'' has introduced or fixed a couple of these. Whether they are to be exploited or patched depends on how NintendoHard you want your X-COM experience to be.
** Sadly, [[GameBreakingBug their evil twins]] are just as commonplace in ''Terror From The Deep''.
** A fun exploit involves hitting certain sides of the UFO with explosives; due to imperfect wall structure, explosions can "leak" through certain parts of the UFO hull. Roast the aliens in their (UFO) shell... [[labelnote:more]]If you're playing the Open XCOM fanmade executable, this bug still works. Have fun.[[/labelnote]]
** Another fun exploit with explosives: you can send Blaster Bombs up into ceilings to force the explosion to the floor above.
** In the older versions of X-COM, you could throw grenades (and High Explosives) through ceilings. With a little Motion Sensor abuse to spot aliens upstairs, you could clip a grenade or a plastique charge through the ceiling and make the floor lava for them. [[labelnote:more]]If you're playing the Open XCOM fanmade executable, this bug was fixed.[[/labelnote]]
** You can stand on a bale of hay to see and shoot through the ceiling at the aliens on the floor above. Especially since that they're usually camping at the top of the stairs to ambush you when you come up.
** The way mind-control works, you control 4-tile units one tile at a time. Aliens will automatically attack mind-controlled units within their line of sight when they move. So the best way to deal with a Cyberdisc or Sectopod is to mind-control one tile. When it moves, it will attack itself.
*** Another fun thing to do with mind-control is to use it on a zombie, then get that zombie killed. The result is your own pet Chryssalid, without all the effort of continuing mind-control.
** Because of a misaimed pointer, all terrain in mountain engagements has the blast resistance of a tree stump instead of their original resistance. In short: EverythingIsSmashableArea. Even the outer UFO walls can be breached with regular explosives! But don't sneeze too hard while still inside the Skyranger...
** An overflow error in the storage inventory data can cause the [[DummiedOut otherwise inaccessible]] Alien Reproduction facilities appear in your storage in the first game.
* InternetBackdraft: The reaction to the FPS reboot was vitriolic enough for 2K Marin and Take-Two to add more strategic and tactical elements to the game in order to placate angry longtime fans. When that only made things worse they announced a Firaxis version which was already in development well before the FPS version was announced and now it gets more attention from the brass as a more apparent sell-able product when it got a far more positive reaction, despite the the fact initial announcement could almost be considered an after thought.
* JustOneMoreLevel: As seen in [[http://www.gamespot.com/x-com-ufo-defense-1993/reviews/x-com-ufo-defense-review-2531954/ this review]], where after experiencing some HypeAversion the reviewer decided to try the game, got addicted and [[TheTetrisEffect started looking for]] [[ParanoiaFuel alien invasion signs]].
* MemeticMutation
** "Where are the Sectoids?" [[spoiler:Depending on where you are in the series, they might be: on Earth and Mars, lurking at the bottom of the ocean in the form of surgically altered genetic throwbacks, working on a doomsday device in outer space while being harangued by Ethereals, trapped in the Alien Dimension awaiting processing into food, on Earth once more and looking very polygonal, sitting in an unemployment centre somewhere in Canberra or Novato, or [[http://www.gameinformer.com/b/news/archive/2012/01/05/february-cover-revealed-xcom-enemy-unknown.aspx up to their old tricks once more]]]].
** The 2012 TBS reboot has Lead Designer Jake Solomon's [[http://www.quickmeme.com/Thats-XCOM-baby/?upcoming "That's XCom, baby!"]] whenever something unfortunate happens.
** Lately people have taken to comparing ''Franchise/StarshipTroopers'' [[http://img.photobucket.com/albums/v204/E-Rock583/rookies_zps2d11a069.jpg to]] [[http://img.photobucket.com/albums/v204/E-Rock583/rookiesskyranger_zps7f83a3ea.jpg X-COM]] [[http://img.photobucket.com/albums/v204/E-Rock583/takepoint_zps0ee5b1ce.jpg to]] [[http://img.photobucket.com/albums/v204/E-Rock583/notasbadasitlooksreally_zps39866c7b.jpg humorous]] [[http://img.photobucket.com/albums/v204/E-Rock583/ricosroughnecks_zps9878a773.jpg eff]][[http://img.photobucket.com/albums/v204/E-Rock583/reactionfire_zps4cca760a.jpg ect]].
** ''"Everyone get back in the Skyranger. Brazil can fend for itself."''
-->'''Penny Arcade''' forum post attached to [[http://lparchive.org/X-COM-UFO-Defense/Update%2029/53-xcom333.png THIS.]]
* MisaimedMarketing: The general opinion regarding the ''XCOM'' FPS is that the X-COM name actually hurts what could have been at least a decent game.
* MostWonderfulSound
** Alien death cries. Every one of them means "there's one less thing on the map shooting at me." The death cry for Snakemen is extra wonderful, as it is the dying cry of the Imps from {{VideoGame/Doom}}!
** In the reboot, just wait until you can build the [[{{BFG}} Alloy Cannon.]] The deep, resonating BOOM is wonderful. And it makes aliens cry with how much damage it can do.
* TheScrappy: Dr. Able Standard from Enforcer.
* ScrappyLevel: Just about any terror mission played at night. Extra points if there're Snakemen/Lobstermen, because you know [[DemonicSpiders Chryssalids/Biodrones]] will be joining the party.
* {{Sequelitis}}: After the original, the overall quality of each successive installment of the series was lower than the previous, regardless of their genre.
** Seemingly averted with ''Enemy Unknown (2012)'', where people seem to agree that, whether they like the game or not, it's very high quality.
* SpiritualLicensee: Wanna see a TV series based on X-Com? [[{{Supermarionation}} Gerry Anderson]] made [[Series/{{UFO}} one]] in TheSeventies.
* StopHelpingMe: The scientist in ''Enforcer'' will leave you with a pathological need to kill him. Sadly, even at the beginning when you can actually ''see'' and ''shoot'' him, it has no effect. The Aliens get to him on Medium and Hard difficulties, in the end, but this lacks some satisfaction.
* TaintedByThePreview
** When the FPS "reboot" was still in development, most of the commentary on the trailers were negative. The memories of how bad previous X-Com FPS was probably didn't help any, either.
** [[http://www.mcvuk.com/news/read/interview-christophhartmann-2kgames/082216 Christoph Hartman manages to shoot himself in the foot with a blaster launcher, and catches XCOM in the blast radius]].
* TheyChangedItNowItSucks
** Both Enforcer and the FPS reboot have taken a lot of flack for ripping out the original trilogy's turn based strategy roots.
** With the reboot now regulated into a spinoff (along with fan complaints nullified by Enemy Unknown 2012), fans of THAT game are complaining that it has shifted from an investigative FPS to a ''Franchise/MassEffect''-styled 3rd Person Shooter.
* ToughActToFollow: See ContestedSequel above.
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