Hm. Well, I would say Final Fantasy VII. I think there were no one emotional like FFVII and no one I reinstalled so often like this to play it for hours and hours, weeks and weeks and made me sad like this game.
Quake III Arena ... I tried out the highest difficult (Nightmare?), when I heard the opponent I died. I just thought "Wow, what the fu**?"
The Heroes of Might & Magic series. No other series moved me at the computer like this series. And it was the first game I tried a LAN-Party. But it's boring, when you have to wait forever for your turn, when one player is sleeping
Die Siedler/The Settlers 1 ... it's just the original for me and I think it's an original in itself.
Eishockey Manager ... the only sport manager game I ever liked. It's easy to handle and it's funny
Ok, there are too much games to list
