Dunno if I'm allowed to suggest themes, considering I'm a fledgling at customizing ponies and I won't likely be entering, but I've recently fallen in love with an indie horror game called Five Nights at Freddy's about horrifying, sentient, murderous animatronics and if I am allowed to suggest themes for swaps, then I would love to see what all you talented people could come up with.
Here is a wiki link to this simple, yet fiendishly, frightening horror game.
[Removed link due to inappropriate content ~ CSA]