A ton of people will sing the praises of Psychonauts but another game that came out around that same time but was somehow given even less attention was a platformer called Voodoo Vince.
I've talked about Otogi and its sequel and that series is one of the Xbox exclusives that do seem to have a small following but NOBODY else seems to have played Voodoo Vince. Vince is a voodoo doll who has come to life and who must save his creator from a neck-beard. The game is made up of clever platforming, imaginative boss fights, a couple of semi-fun vehicle sections, items to collect etc. This is about as Rare as you can get without having your game made by Rare. The big gimmick for this game is a focus on combat and the ability to use screen-clearing Voodoo attacks. They're randomized outside of boss fights but they're still pretty cool little animations. The game is packed full of some pretty good humor as well. It wasn't all dark humor but remember, this game came out when Invader Zim ruled the Earth and it was impossible to escape the awesomeness that was dark humor. Sadly, this is only on the original Xbox and if you own a working one than you're actually in luck since it's inexpensive. It may be available on the Xbox Live store but I have no idea how well it might run. If you have a chance to play it, definitely do so. If you can't, it looks like someone did a lets play of it. It was fairly well received, Game Informer was the nicest to it giving it an 8.5/10, and Gamespy gave it a 3/5...on Metacritic it's sitting at a 73% so use that information however you chose in assessing its worth.