SMASH that LIKE button for Aliens in COD Ghosts!br • Subscribe for DAY ONE GAMEPLAY : •Twitter for Updates: br Call of Duty: Ghosts contains a secret hidden co-op mode called Extinction. Extinction is a 1-4 player cooperative game mode featuring a unique blend of fast-paced survival action, FPS base defense, scavenging and class leveling. What makes Extinction Mode so unique, is the creatures we're up against. Aliens.