Thanks for the comment! It actually started out as an auto runner, but I opted to give the player a little more freedom to retry things. And the fact that it's horizontal was mainly a result of my ignorance. I did not realize how to create slopes when making this, so you get a skateboarding game without ramps, haha.
However, there is a (tiny) secret level with a bit of verticality. (And a bouncing mechanic not found elsewhere in the game.) You gotta select the right board to unlock it. ;)