Nice little game. Didn't encounter any bugs.
What is definitely needed:
1. Health regen/Health pots in shop
2. A visual indicator, that you took damage. For example, red borders, when you're taking damage or classic -1 on top of the head popping up.
3. Maybe a tooltip above shop, that you can scroll through items.
4. And a tooltip on how to use the item, when you get it.
Overall, enjoyed the game.