Haha, one game? I'm a serial game-dropper. I love'em and leave'em.
Let's see. There's Final Fantasy 8, 10, 12, V Advance if you count the bonus dungeon I could never get through, Jak and Daxter (that one friggin obstacle at the very end that I was convinced was the final hurdle, but I just couldn't seem to jump high enough), Radiant Historia, Okage.
These are all games I stuck with right until the end and then gave up for some reason, usually ending fatigue but sometimes "ooooh, shiny, new game"
I have another whole list of games that I just stopped playing halfway through.
I hate having ADD sometimes.