I think you could do some cool things with this. I already had a pretty good score the first time around. I think you could push the speedrun part even further, for example at the start make it almost impossible to beat the game in a short amount of time. For example you can give the player the speed of a turtle initially or you need to take a longer route because your jump is not high enough yet, that would be an easy way to extend the gameplay and could even be funny.
Cute short experience. :D