Aquamarine Gravitino
Your planet is in danger from constantly-spawning red asteroids. Your only hope of avoiding extinction is to launch gravity-manipulating masses into space to deflect the asteroids away from your planet. But the act of creating these masses can take a heavy tole on your ecosystem as is, so be careful.
Left-click to select masses, right click to move them. Hold the middle mouse button to rotate the camera. Click on the planet to spawn a new mass.
Planet and asteroid surfaces generated using http://donjon.bin.sh/world/ .