Hmm, I beat most that I play, but....
Batman Arkham City - I legitimately forgot about it until I read this thread and thought about it.
Enslaved - Played it for like 10 minutes, never again. Had it for like 2 years.
Super Mario Galaxy - Yeah I know, I should finish it. I unhooked my Wii like 3 years ago and have never had a reason to hook it back up cept for this game.
Oddworld Strangers Wrath for X Box 1. Bought it late in system cycle and 360 came out weeks later, so I just dropped the game as result. Game wasn't bad actually.
Metroid Prime 3 - Never even made it to the final boss, just got slightly bored of the game. I have thought about going back and playing it recently oddly enough (with Mario Galaxy), but after hearing someone else bitch about it, I think it can remain on the shelf. (I should go back and finish SMG - I know)
Skyrim. Got 60 hours in, then an Elder Dragon flew over Whiterun. I was like 'fuck it', turned the game off, and haven't played in five months.
Why did that dragon make you quit? Just punch it in the fucking face and keep playing the game.