Alien blaster

The Alien Blaster is a small energy weapon which appears in Fallout, Fallout 2 and Fallout 3.

Fallout and Fallout 2
A strange gun of obviously alien origin. Looks like it can support small energy cells, however.

Locations
In Fallout, the Alien Blaster can be found only in the "UFO Crash" special encounter.

In Fallout 2, the Alien Blaster can only be bought from a merchant that you can meet during a random encounter north of Modoc.

Fallout 3
In Fallout 3 the Alien Blaster is arguably the most powerful gun in the game (The Fat Man is a launcher, not a gun) seeing as the chance for criticals is remarkably high. You will more often than not be able to take down any foe you encounter with one well aimed shot to the head. More or less effective depending on how you developed your character.

The Alien Blaster uses unique ammo that is extremely hard to find. In Fallout 3 the Alien Blaster uses Alien Power Cell ammo and NOT Small Energy Cells as in Fallout 1 and Fallout 2.

Known Weapon Locations
The Alien Blaster can be obtained from the body of a dead alien lying a few feet away from his crashed spaceship. The spaceship is found northwest of Greener Pastures Disposal. It is not marked on the map. You'll know you're getting close when you pick up the "Recon Craft Theta" radio signal.

There is also a random encounter that will trigger the falling of the blaster and ammo from the sky. It's location is variable and is preceded by a green explosion in the sky, similar to a plasma weapon. The Firelance can also be recieved this way. Either way this event is considered rare and there is no known trigger to make it happen. Although quite a few people have reported that it can occur by the memorial in the area around Tepid Sewers.

Additional Ammo Locations
120 shots can be found next to the spaceship. You can also find this rare ammo in Fort Independence, lower level, outcast weapons room[Hard door].

Ammo can somethimes be found in front of the Super Duper Mart that Moira sends you to on the side quest about the Wasteland Survival Guide. These Alien Power Cells lie loose on the ground near the right entry door.

There is also some ammo located further west in the immediate area of the LP8 Broadcast Tower to the west of the crash site. Just check the ground.

Northwest of Vault 101, there is a silo and an abandoned barn(not an identified map location). A small amount of ammo can be found loose along the barn wall and near the car.