Procedural Generation by cloning player moves
X-post from my submission to the recent Procjam.
I released an iPhone game for the October Ludum Dare https://itunes.apple.com/app/id935956154 , where you fight copies of yourself.
I extracted this logic into a Javascript library that lets you record actions of a node then play it back. Try out the web canvas painting demo where each time you click a paintbrush replays what you did.
You can use this to copy player moves into clones like I did for Quantum Pilot or anything else you can think of involving recording actions and replaying them later.