Re: Games started but never beaten.
From what I can remember,
Dark Souls - I restarted the game so many times because I had missed something or didnt do something properly, I just lost all motivation to complete it.
Witcher 2 - Got to the second disc and lost interest.
Hitman Absolution - In the process, but missions are becoming a chore.
Borderlands 2 - Want to complete it with my friends, but just never get round to playing it.
Catherine - Halfway through and lost motivation
Black Ops 2 - Lost interest