I have few suggestions:
-Maybe you could try to add a main menu with different levels.
-Also adding a clear finish point could be nice ( it could be a flag all the way on the top or something like that). And also say to the player that "he won" when he arrives at the top.
-And like someone else said already, maybe a timer for more challenges could be nice.
I hope those suggestions inspire you for future updates or games :)