Wow, you actually made it very far. I understand not liking that you can fall down really far but this is by design. It supposed to be similar to games like Getting Over It and Pogostuck. But these types of games are certainly not for everyone. Maybe it should be better explained in the game but your acceleration is based on the angle you lean. Acceleration increases up to an angle of 45 degrees. You will naturally go slower up hill as you have to overcome gravity. You do have to hold sprint a lot but I don't think the player should be able to go faster. Maybe there should be an option to have sprint the default and you can hold to walk