I've not encountered Sean Howard's Three Hundred Game Mechanics before. Beginning in June this year (and already up to #58) it's a collection of ideas for making interesting games. Not the games themselves, but simply concepts or conceits that Howard would be interested to see appearing in games. With the added suggestion that others go make games based on them.
#10: Time Spy. "A turn based game where you can send a spy to previous turns or even future turns."
#53: Alphabet Rogue. "A roguelike for beginners, where the alphabet is the deciding factor in combat."
Each is accompanied by a longer description of the concept, and its potential, often accompanied by Howard's lovely pixel cartoon illustrations.
Based on #56: White Noise, it's a platform game using a screen of static noise that moves at varying speeds, thus creating the optical illusion of shapes and space. So in the screenshot above, you just see static, but believe me, it's a picture of a stickman leaping across a gap, avoiding the missiles of a wobbly star beast. (And no, it's not a stereogram - for goodness sakes don't break your eyeballs trying to see the patterns).
It's a very simple game, about 10 minutes long and there's no great challenge, but it remains well worth playing. There's something intriguing about how it messes with your eyes (and I think might have given me a headache).
So get to it, indy game makers - let's see some more of Howard's ideas. Especially Time Spy! Oh, and Mr Howard - how about putting links to games that have been made based on the ideas in the posts?