I don't know of a game with intended rockcrawling, but the first Halo game has a lot of exploration possibilities in the offroad truck (called a Warthog) in the 2nd, 4th and 5th levels of the game. The physics of the game are pretty good too. There's a whole scene devoted to videogame tricking. Yes I've played a bit of Halo- see my avatar? 
I was going to suggest that too. Me and a buddy used to have rock crawl comps in halo 1, we'd find a good course and then see who could get to the top first if at all.
Poll
