A few things that I have had in my mind for a while and wantto create, but can't because I don't know how;
How about a survival kind of game, where a skunkess (or other) shrinks people to the size of atoms, and makes them live on their ass.
Or one where someone sits on the player's face, and you have to hold space (or another key) to breathe whenever they let you. You can also struggle and squirm to try and make them move.
Last one; the tail wraps around your head and traps you against whoever's ass as you choke and gag on their noxious fumes :3