Retaliate is a simple space shooter game, a la Galaga. Your ship is locked to the bottom of the screen, and the hostile alien ships attack you from above. The graphics are simple and low end, similar to other classic arcade games.
There's an amusing video at the beginning, and very simple controls.While this game has all the characteristics of a simple arcade shooter themed around classic games like Galaga, there is one unique twist to it and that is the fact you start off with no ammo at all. So you'll have to survive long enough to collect ammo, then you can begin shooting your alien enemies out of space. Like most games of this nature, your goal is to score as many points as you can before you're dead.
The game is available now on Google Play, without IAPs (but the occasional ad will show up after your ship explodes).