CoronBall is a free android game, idea is based on old PC game what I was playing as a child (but I don't remember its name). Game has fun, cartoon-style climate. Players are bacterias and a ball is a virus :).
I programmed an enemy behaviour to be natural, so you can beat it even on the very hard level, it's quite difficul thought (I did it only once and I was playing a lot during testing and debugging). If game will become popular I'll make new levels, add a possibility to change players half, add multiplayer and new some new moves.