The game focuses on the emulation and assimilation properties of the alien, hiding its identity under a veil of fake humanity. The Alien's true objective is to escape from the base, choosing to hide itself and collaborating with humans, or to reveale its true nature, playing ad a monster to openly assimilate all the team members.

Humans must try to survive, maintaining outpost 31 and choosing the best way to escape among the three available, but most important they have to test the other team members to reveal the alien and find who is still human.

The road to victory is truly hard, but not impossible. Be careful though! The parnoia of not knowing who you really have on your side may cloud your decisions!