I myself can't do it (not dedicated enough), but bullet hell games as SharPhoe said and stealth games might take the cake on games that you could or should memorize. Once you can figure out the exact patterns of the AI for stealth games, speed runs become simple. Bullet Hells are more about insanely dense, mostly preset patterns than anything.
[sub]Ah Touhou, if only I could get stuff imported.....[/sub]
[sub]Ah Touhou, if only I could get stuff imported.....[/sub]