I'm going to go with Skies of Arcadia, which is maybe cheating considering I've never actually played the Gamecube version, only the Dreamcast version. Then I would say Sonic Adventure 2...but I've barely played the GC version, mostly the DC version.

If I have to choose a game I've actually spent considerable time with on GC, I'd say SSBM. That's the GC game I've spent the most time on, and had the most fun with, even though I'm not very good at it.

What about Prime 2, then? ;)

On a technical level Prime 2 essentially matched, but didn't surpass Prime 1, so the original was a much higher achiever for its time IMO.

From an artistic standpoint I think Prime 1 was better and regarding the games themselves I think it was far, far superior to the sequel.

/thread

Metroid Prime. Absolutely fantastic experience. I don't believe a more immersive game has been made since.

Hmmm...
Eternal Darkness, F-Zero GX, or Metroid Prime...
Though I also have to give TTYD a lot of love...
It's hard to choose...

Wind Waker - Everything about the game was absolutely fantastic. Wind Waker was the closest thing to Mario 64 as far as a single player experience goes for me. I never got into Zelda games when I was growing up. I played Zelda for NES when I was young, but never owned or played LttP as a kid growing up. I also didn't play either of the N64 Zeldas. I saw a preview for Wind Waker in EGM magazine and it really got my attention. It looked like no other game I've really ever seen before. So I decided to pick it up on day 1 and I was absolutely blown away. I can't say enough about the music (the opening start screen music is something I will never forget). It's the best music in a game I've ever played. The gameplay, the graphics, and just the sense adventure that just blew me away made this game just amazing. The scale of the ocean and being able to sail from island to island just gave me such a sense of adventure I never experienced in a game before. Wind Waker currently sits as my 3rd favorite game of all time.

phantasy star online ep1&2 was just as phenomenal as the dreamcast counterpart that most people upgraded to,

I'm 37 now and still have fond memories, it's my all time fave game,

thank you game cube

The Resident Evil remake since it's platform exclusive, you can't get it anywhere else and it's actually one of the best RE games ever.

Has to be REmake. Great graphics, and the game was geniunely creepy at times. This is the game that got me intrested in the franchise.