It's easy to go without extra energy in those first few levels of REPO, but you'll need some sort of power source for expensive new weapons as things ramp up. That's where Energy Crystals come in, providing a finite number of charges for your Semibot's growing arsenal.
Keep in mind, these little yellow power-ups are separate from the stamina upgrades Semibots can purchase at the Service Station between levels. Energy Crystals are strictly for recharging and repairing weapons and tools. To get your items back in tip-top shape for knocking about more nasty REPO monsters, here's a quick rundown on how Energy Crystals work in REPO.
