From Binary Zoo:
Described as "part Asteroids, part Robotron, and part Paint Shop Pro," this vivid game puts a unique twist on traditional shooter action. The aim of the game is to change the color of the entire screen from black to white or white to black. This is achieved by shooting the alien blobs that color the background when destroyed. There are three colors of blobs to shoot (red, green, and blue) and the color they leave behind changes the behavior of any enemies that travel over it. The more of the screen you color, the more the enemies' behavior changes.
The latest version adds two new power-ups and better ship-rotation control.