X-COM: Apocalypse

Story

Half a century after the end of the second X-COM campaign, the final battle of T'leth severely damaged the Earth's biosphere. As a result, several self-contained megalopolis-type cities were proposed to serve as habitats for humanity. The game follows Mega-Primus, the first of these cities, built on the ruins of Toronto, Canada. Meanwhile, the off-world colony of Mars is being exploited by the Elerium mining corporation Solmine and suppressed by MarSec (MAR's SECurity). The alien threat in the game is represented by a new race of organic, extradimensional aliens that initially appear to have no connection to the aliens of the previous two games, although later missions set in the aliens' home dimension reveal that they have enslaved surviving Sectoids. These new aliens attack the city through tetrahedron-shaped teleport gates. The player must figure out how to send his/her own plane, along with X-COM agents, through these gates without being destroyed and bring the war to the aliens. There are 14 races of alien beings in Apocalypse, including anthropods, brainsuckers, hyperworms, megaspawns and micronoids. Each race has different strengths and weaknesses, and some races depend on other races. The "alien life cycle" plays a crucial role in the game. The player learns about this "alien life cycle" through research and especially through the low-level attacks of the aliens while collecting specimens. Most notably, the attack of the armed alien, the Brain-Sucker, which attacks individuals after landing from a pod launcher used by alien foot soldiers. The Brain-Sucker hatches and attacks the closest individual by jumping on their head and seemingly injecting something through their mouth, whereupon they immediately die. The life cycle later takes a mysterious turn, showing no connection between the lower alien forms and the higher alien forms. Eventually, it turns out that the leaders of the invasion are the micronoids, a race of intelligent single-celled organisms that live in the bloodstreams of the other aliens. The ultimate goal of the invasion is to inject the micronoids into the bloodstreams of important personalities so that they can control Mega-Primus through psionic domination of their hosts. Finally, the player has the task of invading the aliens' homeworld and destroying their side of the gate, because this is the only way to stop the Micronoids invasion.