This is a good first pass at a game. Things to fix : How close is the grim reaper behind me? Does getting a speed boost make him farther away? Do the unlocked avatars give me any kind of advantage? When sliding the camera angle is terrible. Is there a way to make it moveable?
Normally in level based games, if you're struggling with a level you can go back, master older levels, and gain more upgrade points so you have greater abilities. That doesn't seem to be the case here.