The game received a new update now. You can access the inventory(press 'I' button on the keyboard) to see weapons and health potions. You will get new weapons when you complete levels. You can equip 3 types of items, weapons, shields, and potions. You begin each level with 2 health potions. I still thinking in change that to be able the player found health potions in chests, but I don't know yet if I will do this. You don't need to access the inventory to use Health Potions. Just press 'U' button on the keyboard to use them instantly.