Valve

Left 4 Dead 2’s fear is kinetic—getting separated, hearing a special infected before you see it, and watching your escape route collapse under a wave of bodies. The game turns teamwork into a survival mechanic: the second you stop communicating, the apocalypse cashes the check.

The AI Director makes sure you never get comfortable—ammo dries up, a special infected yanks someone into the dark, and suddenly the plan is gone. Left 4 Dead’s best scares are social: the moment your team fractures and you realize you’re not surviving alone.