The Trope Codifier, along with Teleporting Keycard Squad. Also has nothing to do with being closeted. Not to be confused with Things That Go 'Bump' in the Night, or the film Monster in the Closet.
Why is there a random closet in the wall that isn't being used?.One must question a few aspects of this situation: Some classic and throwback first-person shooters still play it straight, however. And it's mainly present in older first-person shooters, as it's become largely discredited thanks to better storytelling techniques or being replaced by offscreen or onscreen spawning.
You pass an innocuous-looking piece of wall, and then suddenly – SHOOM! The wall opens behind you to reveal a two-foot-by-two-foot square that's completely empty, except for a demonic space monster trying to burn the back of your head off. Say you're a Space Marine in a completely normal space facility.
