If I may suggest more than one possible them to choose from, I have a couple in mind, since this looks very exciting.
Theme 1: Laboratory. Wake up to find yourself in a perfect white room with all utilities and comfortability for modern living, classic cliche, the door opens and you decide what to do next.
Theme 2: Haunted House. (Wow who would expect this one). In front of a house's gate, already feeling wary of entering the house, you need to go inside for some reason, I don't know why, maybe you're just the typical dipshit in every horror movie.
Theme 3: Survival. Be it zombie apocalypse, aliens, or post-apocalyptic survival. Taking rest in an abandoned building, you need to gather food and supplies, for what? Survival (surprising right?). But you are met with a variety of obstacles in your path.
Theme 4: Mind Warp. I guess this can be seen as different things, but what I'm aiming it is more of sort of "supernatural" or mind bending levels that don't seem real, but as if it's happening in your head. Of course using logic, and tools given to you to opt your way out of the situation.
Those are my suggestions for now.
