The alien blaster is a weapon of great extremes. It has the highest damage-per-action-point of all single-shot weapons in both Fallout and Fallout 2, as well as the second-highest ammunition capacity of all single-shot weapons in both games. It is also highly accurate. Offsetting these strengths is its extremely short range of 10 hexes, the shortest of all ranged weapons in Fallout and the second-shortest in Fallout 2.
This weapon can do the highest single-shot damage possible in either game -- a perfectly lucky critical to the eyes will do a crushing 360 Hit Points of damage (381 HP if the player has taken the Living Anatomy perk and two ranks of Bonus Ranged Damage) -- being thus capable of killing anything save the end bosses with one shot. Such hits are extremely rare, occurring only at the top end of the gun's massive damage variation, however, an average eye critical (rolling 51 on the critical table) will still average an impressive 180 HP. The alien blaster can be fired for 2 action points with Fast Shot and the Bonus Rate of Fire perk.
Despite its alien origin, this weapon commands the very high price of 10,000 caps in both games. All its stats were left unchanged in Fallout 2, however, the weapon's combat value is not entirely identical in the two games. This is due to the fact that floaters, which are encountered quite commonly in both games, were made extremely resistant to electrical damage in Fallout 2. As a result, the alien blaster and the other pulse weapons do very little non-critical damage against them. Most critical hits bypass this problem though.
The alien blaster can be bought from Willy in a random encounter north of Modoc.
Additionally, the alien blaster can be picked up by hacking a terminal on the Enclave Oil rig in the maze room. By passing the Science check when using the Repair skill on a (each game randomly selected) maze room terminal one can find an Easter egg. The egg 'hatches' a special item depending on the Chosen One's tagged skill. If they have Speech tagged and over 100% the egg is the alien blaster. Note that the game checks from the ordered list (science, repair, gambling, outdoorsman, throwing, first aid, doctor, traps) first for a tagged skill over 100%, so in order to get the blaster one musn't have any of these skills tagged and over 100%.