You must defend the gold core of your world from a barrage of missiles. Use the left and right arrow keys to spin the world.
Each missile's color matches the terrain type it will do the most damage to, so spin vulnerable regions out of the way. Yellow missiles do serious damage to all terrain types.
Missiles that hit water will slow down and do less damage. As you successfully guide missiles to the appropriate terrain, you'll see bonuses light up below. When these are fully lit they can be used with the A, S, D, and F keys.