Prey

Prey is a 2006 first-person shooter game developed by Human Head Studios, under contract for 3D Realms, and published by 2K Games, while the Xbox 360 version was ported by Venom Games. The game was initially released in North America and Europe on July 11, 2006. Prey uses a heavily modified version of id Tech 4 to use portals and variable gravity to create the environments the player explores.