As we know along with the success in many games comes defeat as well. So can you post which are according to your opinion the great games, which you never actually beat.
From my humble experience I can point out that I have a very bad habit of stopping 85-95% through them. Worst offender is probably Valkyria Chronicles, where I'm the last or next to last mission.
Fianl Fantasy 12...had it pretty much at the last level and said "I'm done!"
XCOM: Enemy Unknown
What about you?