I have a ton of games I never finished, but most of them I bought just because they were cheap.
Now games I planned on finishing.
Ninja Giaden ( I think a better game came out so I switched)
Kotor 2 (I couldn't find the guy I needed to talk to, I don't believe in strategy guides, I was young at the time)
GTA 4 (It got pretty boring)
Prince of Persia, The second one, warrior within I think? (I just don?t know, I liked the game, it played well, good story, I just never finished it? maybe I should go do that now)
Gears of War (about 3-4 levels in, I really didn?t care, sure it?s a well made game, I just didn?t see a need to finish it)
Jak 2 ( I was about nine years old, could NOT beat the last boss, had to get my cousin to do it, never saw a reason to go back)
Pikmin (Didn?t have trouble with the game, I broke the little Game cube disc , never bought a new one)
All I can think of right now.