It's a very good idea and visually it looks great! to improve the experience a bit I would recommend to put the offense on the right of the scene because when you get to buy the upgrades you just enter the ‘garden’ and you don't see what you are really upgrading, and also that when upgrading the backpack it takes longer to go slower because with the upgraded speed and backpack also with 25 coins I was going too slow and it was even difficult to jump to climb out of the cave.
Anyway good game, congratulations!