Remember the Star Trek: The Next Generation episode "Remember Me", where people start disappearing and only Beverly Crusher notices, until it turns out that the universe is collapsing in some sort of phase bubble because the fools in Engineering were messing with the warp core yet again?
You could say she was... running out of space.
My concept is loosely inspired by that episode. The fabric of space itself is collapsing, and ... though some mechanism ... the player has to stop it.
For the moment, I've got a mockup of the player and the spread of collapsed space-time:

Not sure how much farther I'll push on tonight - I might have a clearer concept of where I want to take this after a good night's sleep. The altered start time is confusing me a bit as I'm having a hard sense of gauging where I should be compared to my progress in previous LDs.