I'm gonna up you all with one title... Beyond the limit: Ultimate Climb, released by Microsoft. Search it up on youtube, and you will get one whole video related to it. (Try for just Beyond the limit, and you find nothing). Only one video of the game is available on youtube. It has earned its place in the collection of obscure games.
By the way, it is indeed a climbing simulator where you meet bears and snakes and ride through caves in mining carts. Here's the one video you will find of it. It's its commercial.
Much less obscure is Bad Mojo, but at the same time it's also much better. You play as a guy who gets tranformed into a cockroach. Then you have to survive in an extremely nasty environment. The game's fantastic, and still pretty obscure. I figured it might at least be mentioned here.
....
Disney's Classics 3-games-in-one DVD with Toy story 1, Timon & Pumbaa Burper and Donald in Cold Shadow.
Oh my god, they released a 3-in-1 version? That's such a deal! I used to love Toy Story and Cold Shadow (...I STILL love Cold Shadow, actually; it's such a fantastic game.) I never got Timon & Pumba. I tried it, but it didn't seem as good as the others. Was it?
Also I'm amazed that some people consider games like Psychonauts, Odinsphere, King's Quest and Ikaruga obscure in any shape or form. I'm not being condescendent here, mind you, only surprised. Most people posting have some pretty obscure games though.
@Aiden Raine: I've been thinking about trying out Grim Grimoire for ages. It looks like a more layered and complex version of Swords and soldiers! It's well worth the price on PSN, i presume?