Get the two aliens to the end of each of the 30 challenging levels. Maybe not as easy as you think because the aliens are on opposite sides (one up one down) of the landscape and you control both at the same time.
Get each alien to its own colored exit at the end of each level. But first you'll need to get the key to unlock the level by getting the required number of colored diamonds on each level. Controls: Keyboard - WAD or arrow keys to move and jump. R key to restart level. Controller - D-Pad/Left Stick to move A to jump B to restart level. Touch - Use on-screen buttons to move and jump.