UFO Defense is a fun reaction game in which you have to press left to shoot the white space aliens and UFOs, and press right to shoot the black ones. If you use the wrong bullets, the UFOs and space aliens will only grow stronger and take more hits to pop. Can you blast them all away before they get too close to you? Once all the space aliens and little UFOs have been defeated, the Mothership will descend for the attack! Are you ready?