Owen Goss (creator of landformer) posted this great game idea generator on his blog today: http://www.streamingcolour.com/blog/game-idea-generator/
It reminded me of a game idea generator I built a couple years ago in Flash(back when I was making Flash games), so I decided to remake it in javascript and post it too. You can check it out here: http://struct.ca/game-idea-generator/
Lemme know if they give you some ideas!