The gameplay is simple and effective. Use the [arrow] keys to move your formation through the sky in unison. They automatically fire downwards so all you need to do is line up shots and keep at least one unit alive. You start off blasting crowds of pedestrians, but soon you'll be taking flack from tanks, missile silos, and fortified buildings. The sheer volume of enemy fire effectively produces the game's feel of an air raid on a war torn planet. Fortunately, the increase in your fire rate with each unit lost balances things perfectly. Trust me: you'll be taking a pounding.
The game isn't quite at a finished polish yet. The cutscenes of your barbaric troops between missions contain poorly written, none too subtle dialog. The visuals evoke a bleak feel, but the short music loop breaks the spell. I encountered a bug only once, but it caused me to lose my progress. However, the fresh concept and an infinite survival mode for replayability overcome these detractions. If you've ever wanted to see things from the side of the Space Invaders, now's your chance.