X-COM: Apocalypse is the third game in the X-COM series, developed by Mythos Games and MicroPros. The release of X-COM: Apocalypse took place in 1997. The game differs somewhat from the previous two installments: X-COM: UFO Defense and X-COM: Terror From The Deep. Notable changes include the introduction of real-time gameplay, although the canonical turn-based mode is still present.
The year is 2084, and things are bleak on Earth—a result of an ecological catastrophe that has made most of the planet uninhabitable. The only place where people can barely exist is the giant metropolis Megaprime. Like any city, Megaprime has areas where ordinary people are better off not venturing. Crime reigns, the mafia operates, gangs rage, and a dangerous drug called Psyclone spreads. The slums are what they are. To somewhat delineate the good and bad areas, the Megaprime authorities build high walls around the hotbed of criminality, but this is not a panacea for all woes.
Overall, life in Megaprime is not great, but it gets even worse when aliens show up. First, reconnaissance bots visit the residents of the city, followed by combat units. Realizing that handling the invasion in the usual way is impossible, the Megaprime authorities turn to X-COM for help. Only this organization can save humanity from total destruction.
In X-COM: Apocalypse, the antagonists are not sectoids, but micronoids—microorganisms that have subjugated the sectoids. It is the micronoids that are behind the invasion of Earth. However, they carry out the plan to conquer the planet not with their own hands (which they simply do not have), but with the limbs, tentacles, fangs, and claws of specially bred biorobots: anthropods, skeletaloids, spitters, poppers, overspawns, and so on.
It should be noted that at the initial stages, X-COM's resources are quite limited, but studying alien technologies works wonders. The organization advances so far in scientific and technical terms that at one point, the balance of power shifts—it's no longer the aliens attacking, but humans themselves. In the end, X-COM units reach the hostile planet and destroy it, thereby putting an end to the bloody war once and for all.