most of them. i have a huge backlog.
here's a small selection with reasons included:
Escape From Monkey Island (worst game of the series, no interest)
Super Mario Bros 3 (that damned pipe world)
Super Mario World (couldn't beat Bowser then)
Super Mario 64 (no idea why, guess i got sidetracked)
Super Mario Sunshine (currently at it again, i ragequit then)
Zelda A Link To The Past (got stuck after the first dark world dungeon i think)
Zelda Ocarina Of Time (on Virtual Console; i only play the 3DS version now and that i've yet to finish too, but i'm very far)
Zelda Twilight Princess (doesn't grab me like the above installments)
GTA San Andreas (the constant gangsta slang got on my nerves along with that stupid army base mission)
any of the Call Of Duty games (but have lost interest in them since anyway)
Morrowind (why??? i always get sucked-in and at some point sidetracked)
Indiana Jones And The Fate Of Atlantis (can't remember why, i was already in Atlantis, hey, i think a reinstall is in order NOW)
Knights Of The Old Republic II (i screwed up my character by making some poor leveling choices and by the time i got to the final planet, he was just too weak and i decided to let it be)