Some of gaming's deepest, darkest horrors are also some of the most patient. Whether it's the Alien uncoiling from an air vent or Nemesis crashing through a window, an unstoppable, unknowable beast can be the cornerstone of what makes survival horror so damn horrifying. These immortal stalkers are predators, and you are their prey. They're not bosses in some RPG to be fought at your leisure, nor dexterity challenges to be overcome with practice. They're primal forces, sinister and endless, and the best you can hope for is survival.