Level 12: Callisto Tower Colony
Enemies: Medium Hulk, Super Hulk, Driller, Heavy Driller
This level consists mostly of a wide open room with a large tower in the center. From the first door snipe the Super Hulks in the wall to the right. In the alcove at the bottom of the tower you’ll find a couple of Drillers. In the bottom corner of the outer room there’s a Robot Generator. When you pick up the Shield Booster in a far corner the generator will activate.
An Energy Center is located about half-way up in one of the outer walls. The Blue Access Key can be found by going through the door in the corner at the bottom of the outer walls to the left of the Red Door. Fly up to the top of the tower and go inside. The Blue Door is to the left.
Go through the Blue Door and take out the robots. The Yellow Access Key is found down a tunnel to the left. Go through the door to the right for Invulnerability. The wall behind it is a secret door that leads to the Hostages. Go back to the central tower and through the other door that leads to the Yellow Door. There’s a Robot Generator on the other side.
Go through the door to the left and down the hole in the floor. Take out the Super Hulks and pick up the Red Access Key on the other side of the scaffolding.
Head back to the wide open room and open the secret door at the base of the central tower for an Invulnerability and then go through the Red Door.
Reactor: Take out the Heavy Drillers and Super Hulk and then destroy the Reactor.
Exit: Behind the reactor.