Hallo, Herr Smol. I will write a review for you.
1. The game demo is very good however, when you're in the cave and your head is above a spike you still take damage. What I recommend is that when your feet touch the spikes you take damage.
2. The shop menus still play the purchasing sounds even when you have no money. This can be an easy fix and all you need to use are Booleans for this.
Other than that. The game tis good. Music makes me go YES. Gameplay and spike dodging makes me go YES.