Wow - I think I'm going to risk bringing down the wrath of every American gamer alive and say just one:
Star Wars: Knights of the Old Republic
I don't think I'm a jaded gamer - I find the good in a lot of games virtually everyone else seems to loathe. But my brain just locks up at the cognitive dissonance between KOTOR: the hype, and KOTOR: the reality. I wanna like it, but can't. To me, it's a jumbled mess of nice ideas that aren't really innovative except to narrow audience, feels rushed, some of the worst cut-scenes ever for this generation (in a story-heavy game to boot with tons of cut scenes), and the Xbox version tech quality is shoddy and far below what the Boxen can do. Halo, hell even GTA, isn't force-fed down people's throats as the "BEST GAME EVA!!!" like KOTOR is. I think of every game this generation, KOTOR is the only one I'm honest to God jaded about.