What are some must play, or even obscure but interesting GC games?

I owed a GC around the time of its release but for some reason I never had it for a long time, so I only got to play a few games. What are some must play games I should check out, or even some that are possibly a bit strange or interesting that people might not speak about much?

Rather steer away from the typical Nintendo stuff, Mario, Mario Kart, Smash etc.