When you upgrade battery, you get free sleep recharge, idk what happen if u run out of energy since energy is almost unlimited (you use less than what you gather), you cant buy the teleportation orb
+, I've beaten the game with 11 energy with upgrades damage/speed at the cost of 16/24 only, means, 100 bucks makes it able to beat it (one or two run tbh) balancing is kinda broken, would be better to have different upgrade, such as speed, more minerals that are harder maybe and pay more, or whatever..