In no particular order.
Half-Life 2: I never got into it. While it was a decent shooter, it didn't do anything different besides add some puzzles into the mix. The puzzles though got annoying. Some of them, like Ravenholm were really fun to do, but a few puzzles, like one of the later ones in Water Hazard, was more of an annoying scavenger hunt. This game was decent, but it's Where Do I Go Now? moments really lowered it's score for me. Decent, but no where near it's Cult of Personality.
Grand Theft Auto San Andreas: This game, was just not fun... at all.
Fallout 3: While this game was pretty good, the whole wanderer thing got kind of annoying quick. I hated those long walks that took forever, and those moments where you forgot to save, and lost fifty minutes of hard work. Not to mention the gun play, as most weapons besides sniper rifles had no range at all and often you had to waste ammo to reach out and pop a head. While the game was somewhat enjoyable, it's bland environment and boring story really ruined the 10/10 expirence everyone else had.
Borderlands: This game was just boring. Your missions didn't seem to really make sense, the whole idea of thousands to millions of weapons was just annoying and not that big of a deal. Borderlands to me was just a bad, bad game. I didn't like it all, and it was just not my cup of tea.
Battlefield 2: If I don't get flame for not bowing down before Half-Life 2, or not dressing up like a gangster and swearing my loyalty to San Andreas, I'm going to be assassinated for this. Battlefield 2 really had awesome potential, but the whole idea of vehicle warfare, with arcadey gun play, and the clunkiness of the mouse and keyboard (yes I know, not liking the mouse and keyboard is illegal), really didn't work out for me. While I could fly a jet for maybe thirty seconds without crashing, it seemed some people could get into a jet, watch the Godfather trilogy, take a dump, read the Bible, take a nap, then go spawn kill me over 9000 times, before I even had a chance to respond.