You move simultaneously two shooting things, one on a vertical line, at the right of the screen, the other on the horizontal line, at the bottom, and you must shoot everything that moves, before, flying and boucing around, it crashes on you. When you clear the zone, you progress onto the next, which is harder and there are some new creatures.
It's not bad, with decent sound effects and presentation, but I found it a bit difficult and lacking variety.
2/5 for now, but it could get better, playing it again.
