Nihilanth is a tough creature to beat. He sends out deadly electrical charges, as well as mobile teleporters. You'd be wise to avoid these. A shot from the Hornet Gun will get rid of them, as will hiding behind the various spires in the room. If Nihilanth does trap you with a teleporter, there are three areas you'll be sent to.

	To kill Nihilanth, you must destroy his power source.

The first area is a large spiral tower. You must make your way to the teleporter at the top. There are some supplies here, so get them while you can.

The second area is a small cave filled with flying creatures and rocks that float up to a teleporter at the top of a vertical shaft. There are some supplies in the blue alcove. Jump on any one of the rocks as it rests on the ground, then ride it up to the teleporter.

The third area is a platform around a pool of water. An Ichthyosaur dwells in the pool, but you need to land in it if you want to survive the fall. Kill the grunts and use the organic trampolines to bounce up to the teleporter. Subsequent teleportations will bring you back to this area, with a Gargantua you must fight.

To kill Nihilanth, you must destroy his power source. If you have enough rockets, shoot the orange glowing crystals on the wall. Two shots should do the trick. There are three crystals, and you can use any of your heavy weapons to destroy them. Once the three crystals are gone, start firing at Nihilanth. When his energy disappears, use the trampolines to bounce up above him. His head will open. Fire into his vulnerable brain (a rocket would be most useful here). When he's destroyed, you've won the game.

Now you'll be given a choice by the administrator. Each leads to a different ending. Good luck on future assignments, Mr. Freeman. It's been a pleasure working with you.