Alien Invasion

You are the spaceship and you are trying to get rid of the aliens. The yellow ring that appears in the middle of the screen every 15 seconds will give you +5 health. Left-click to shoot at the aliens and use the arrow keys to move. The green boxes spawn more aliens and the orange boxes give you +1 health. If your health is 0, you lose but if you get a score of 1500 before you die, you win.
#shooter