BF1942 as a multiplayer I play more than anything else, must have played over 1000's of hours of it. But that doesn't count I guess...
The legend of Zelda (some don't call it and RPG) Ocarina of Time. I've finished it about 10 times.
Goldeneye, must have clocked up 100's of hours on that, it's just too fun.
Tetris, who knows, I may have spent my whole youth playing it...
Shortest time ever on a game that i actually gave a chance - Prince of Persia, Sands of time. The game was so unbeleivably frustrating, unresponive controls, really bad cameras, terrible acting, everything about it made me wanna puke. i spent maybe an hour before uninstalling it.