It requires a special event to happen in the game, which may be randomly activated, so players can't simply acquire the weapon at their leisure. Whereas finding the Alien Blaster Pistol in Fallout 3 was simply a matter of making one's way to the alien crash site, obtaining the weapon in Fallout 4 is a bit trickier. Players have a large arsenal of destructive tools at their disposal in the game, with one of the rarer and more interesting guns from Fallout 3 returning in the form of the Alien Blaster Pistol - albeit with an updated look.
The Fallout franchise is full of awesome weapons, and Fallout 4 is no exception.
A seemingly random event in Fallout 4 gives players the opportunity to find a crashed alien spaceship and then acquire the Alien Blaster Pistol weapon.