If a block is lost, it stays lost for the rest of the game. If B is lost, all lights go out, if C is lost, you cannot recharge batteries, if G is lost, you cannot reload weapons.
Battery is health.
This is a first-person shooter where you move around in tiles, rotate 90 degrees, and control an aiming reticle while holding down a button. It takes place in a large space station, in a bunch of corridors that all look the same. I thought it was neat at first, but I couldn't find a map or a way to recharge my weapons.