If you still intend to play it OR if you already beat the game, it doesn't count.
I'll start:
- Soul Calibur Legends - I only got it so I could play as Lloyd but I couldn't even get that far. It was just too unenjoyable >_<;
- One Piece: Romance Dawn - I really like One Piece, but the game is just too bad. Gameplay is dull and repetitive, the narrative is boring, it requires grinding and crap... ugh no I couldn't. Maybe if I could cheat and just boss rush everything, maybe, but I don't even know what the point to that is. The only real good part about this game is the music.

For me it's really hard to drop a game (I try to finish what I start) so when I do it's gotta be at an extreme. I usually pick games I like etc. so it's rare I have to drop stuff but sometimes I make a bad purchase knowing it's a bad one (like the above two--I had heard they were bad games but I still got them because of the appeal as a fan) and as a result I give up mid-way or something, like here.
I managed to pull through Project X Zone (and I mainly got that for the cameos and such) though so it's not always hopeless. Then again that game wasn't nearly as bad as One Piece: Romance Dawn (and yes it does pain me to call a game based on my favorite manga of all-time bad).