Vanilla Skyrim - It had less replayability than other TES titles, it became a complete ARPG with roleplaying being almost thrown out the window, it's the weakest Elder Scrolls experience to date, but that didn't stop sales for some reason.
Black and White 2 - I have no idea why they made this, it's somehow worse than Black and White 1, I liked the original for being an experimental game, two just reeks. I wish Lionhead didn't go under, Fable: TLC was a decent game, but after that I just lost interest in their games.
Battlefield 3 & DayZ or any FPS with cheating for that matter - Cheaters ruined the online experience. It's frustrating getting one shot in the head by a magnum gets old really quick. It's a love-hate relationship with multi-player.
Any Final Fantasy game other than VI .VII, XIII and Lightning Returns - Maybe it's because I haven't played them, the characters of the other titles look meh to me, when I saw the gunblades in 8 I just cringed so hard.
Diablo II & III - THE GRIND! OH MY GOD. I had already burnt out on MMO's like Runescape and WoW, HELL NO, STAY AWAY FROM ME! PS. To be fair they aren't bad games, but grinding after beating the game just to try and get better loot and not get killed on higher difficulties takes more time than I am comfortable with.
MechWarrior Online - It's not the same anymore! IT'S NOT! Ever played MW4:Mercenaries with MekPak? That's much better, the graphics are dated, but WHY DID THEY CAN MechWarrior 5!? TO MAKE MORE MONEY! I've been waiting for MechWarrior 5 for so long and it's campaign with the possibility of co-op. Now I'll never see that game. I went from not being able to pilot a Mech at all as a kid and not liking the Mech sims, now I am a better pilot and in love with MW2, 3 and 4.
System Shock 1 & 2 - Clunky controls wouldn't let me play more than an hour of these. What a shame.
Last but not least, sewer levels in video games. Even Serious Sam 2 tries to joke about it.