Homeworld: Yes it was fun, yes it was interesting to play but my favourite aspect was the fantastic asthetic quality. This game is a work of art.
Freespace 2: The first time you hear a beam cannon powering up and you can feel the hair on the back of your neck standing on end.
Halflife: The game that keeps on giving and the biggest shock I've ever gotten that a game could be so immersive. Utterly captivating.
Xwing vs. Tie fighter: Tell me you didn't feel like a hero whilst piloting an Xwing.

The missions ruled and so did the music.
Soul calibur: Heart pumping mental fight action. Other than the next game nothing's got me so on edge.
Tekken 3: Moves moves and more moves. Great characters too

Pod racer: It actually
feels like you're travelling at 300kmph.
Bomberman (SNES original): Playing with 3 of your pals at the same time everybody attempting to off each other in the most simple and fun game. I'm pretty sure this game has wrecked relationships

Shenmue and Shenmue2: Character interaction. The characters were so believable, diverse and interesting. The story was brilliant too and there's a third game in the works. *bliss*