The lightning bolt was Energy, and was used for Abilities. You hold Right Click on a Metal and it activates it. Some target a tile, and some activate right away. It's the most unintuitive control I have in the game, but since I wanted to stick to just the mouse, it was difficult to make a way to use the ability without a popup menu every time.
SHOT's just way too OP and the others are too underpowered right now. I'm currently changing them for a full build, so the issues should be fixed by then.
Thanks a ton for playing and enjoying! :V