Mono

The excellent shooter Duo features a two-directional gun with enemies and weapons based on mathematical functions. Binary Zoo's follow-up uses similar elements and a unique treatment of colors to create a one-of-a-kind gaming experience. Start with a black or white screen and then turn it into its opposite color by shooting colorful blobs that paint the screen as they explode.

Auto-fire is selected by default. You can turn it off and use the left mouse button to fire manually, but there's no reason to do so. The right mouse button allows you to rotate your ship. Since the mouse moves the ship as well, directing your shots takes some practice, but it quickly becomes second nature.

As the screen changes color, your enemies are affected. Red makes enemies return fire; green speeds them up; and blue makes them home in on your ship. All of this is rather extraneous, however, since you'll be too busy moving and firing to pay much attention to what the heck's going on. The easy and normal levels aren't much different, but playing on hard is psychedelically masochistic. Don't worry when the screen starts to pulse and throb. It's supposed to do that.