In Space Boom! you control a space jet and you have to defend the portal at all cost. Massive enemies will spawn from the black hole and it's your job to destroy them. Collect or shoot green gems during the level to upgrade your weapon. Avoid the laser, it will destroy you. Make use of your speed bursts to reach the other side quickly. Get ready to destroy the aliens and their home worlds, and stop them from hitting your ships warp ring which will weaken and destroy you.
Your ship rotates around the warp ring and fires automatically. Control the move direction by pressing the left mouse button or Z. Speed up your jet by holding the right mouse button or X.