Very neat concept! Reminded me of the original Donkey Kong a bit. Pretty cool how it got much harder when the mountain was steep. I did notice a slight bug; if you walk all the way to the left off-screen and keep going, the character disappears from the screen (falls off the map? I'm not sure) and isn't hit by the boulders. Then the camera goes all the way to the finish and you win automatically. Also, I think it would be cool if there was someone at the end throwing the boulders. It could be fun to beat the game and reveal who the enemy was, to add a bit of story. Overall, great job!