I guess the fastest time that i took to finish a game was Pokemon White, i think i finished it in a few days.
I forgot all about that game but it was this for me too now that I think of it. My buddy had gotten this game when he bought his PS2 but neglected to buy a memory card so we had to beat it in one sitting since we couldn't save. Think it took 2 1/2 or 3 hours.I finished The Bouncer in an hour and a half. Shortest game I've ever played.