The autoaxe is one of the new weapons in Fallout 3's downloadable expansion The Pitt. The autoaxe is kind of like a chainsaw and an axe combined. Four axe heads spin in a circle like a wheel at the end of the weapon. There is also a perk that goes along with the autoaxe, and will increase the weapon's damage.Fallout 3 Wiki: AutoAxe

The tale of The Pitt begins when you get a distress signal on your PipBoy radio from an escaped slave. The slave tells you about the situation he escaped from, which includes a gang of slave masters and a gang of slaves. Some of the slaves have turned into mutated beings, and rumor has it that their masters have found a cure.

An underground railroad must be used in order to get to The Pitt, formerly known as Pittsburgh, and see what you can find out. On your way to The Pitt, you must give up your equipment for a short period of time and learn how to use an autoaxe. You'll be forced into a death match in order to move on into the city, which consists of a few different parts. There aren't any vendors, and really no reason to return after you've completed the quests.Fallout 3 Wiki: AutoAxe

• Gametrailers.com: Fallout 3 - Exclusive Debut Trailer: The Pitt (Time: 1:18)