Any recommendations for obscure gamecube titles?

I have all of the games that are well known for the gamecube,but are there any obscure titles or hidden gems you would recommend

Bit vague, because what's well known and what's not. Viewtiful Joe and Timesplitters are pretty well known names, so I think you've got those. Eternal Darkness is pretty much a must have. If you haven't played Beyond Good and Evil, get it. I don't have Killer7 and Geist, but those seems like a pretty obscure games. Ikaruga sounds like an awesome shoot'em up.

Not a good game from what I've read, but I'm still looking for Space Raiders. The idea sounds intriguing. It's basically Space Invaders in a Third Person Shooter shell. But it's pretty rare.