Here's my theme suggestions:
Comic Books
Create to do your bidding
Paper and Pencil RPG
I deleted my third one and made "Comic Books" just because that would make my game idea pretty easy lol
"Create to do your bidding" I think would be cool because it can be viewed in many ways. It could be Overlord type games, tower defense, necromancy, a "God" type of game (e.g. Black and White) or even procedural generation.
"Paper and Pencil RPG" would get a lot of rpgs being made. However, D&D is not the only rpg in existence. On the flip side, people could also make game with a paper and pencil game as a reference or even a game about people playing a tabletop game.