"Marine, we need you to head to the depths of the compound to rescue a scientist that is being held hostage by Makuta and his manyfold minions. Here's your pistol and eight rounds of ammunition. Good luck."
Somehow, the world, or at least the city you are in, has had its inhabitants slaughtered and resurrected with a hunger for brains, or their murderers have minions trying to find any survivors; i.e., you. Your goal: Don't die before help arrives or before you reach an exit. You will have close escapes from horrible creatures. Things will jump through windows at you. There is a chance you will probably die. Unless you have half a brain.
RPGs that use this trope: