Bombs explode across the screen either diagonally or both vertically and horizontally as indicated by the mark on their face. Simply drag and drop them from the inventory bar at the top onto the grid below. Lots of happy explosion things will occur, and enemies will turn into dust!
Each enemy has a hit point counter on the lower right side. Your job is to bring that counter down to zero. Bomb blasts that hit enemies reduce their health by one, and if you want to get a perfect score for each level, you'll need to hold back on bombing foes with no health.
The grid is small, the enemies are small, the number of bombs is small, but the challenge is anything but. You're constantly second-guessing your moves and trying to decide if a series of bombs' explosions will overlap in a good way or a bad one. Getting the gold star is another matter entirely, forcing you to consider not only each bomb but the state of the entire grid after each explosion. It's no tiny task, and thanks to the open puzzle selection menu, you can hop back and forth and try any stage you please. No pressure, just ouch-my-brain-inducing bomb placement.