This is a "shoot-them-up" kind of game, filled up with flying saucers. Destroy them all before they destroy you and planet earth! You can play as long as you want in the demo mode, till your space ship explode. 2 levels : earth and mars, the waves are infinite and of course : it's more and more difficult! If you unlock it, you get access to the improvements pages at each wave completed. Way more fun. Link to Google Play store