I like to think this is what AvP would've been like if the developers included the shotgun into the game.
This is a recording of the MelPyth mod, which is a mod for AvP Gold Edition. It adds a shotgun (SPAS), as well as some nifty multiplayer commands. The mod will technically run on AvP Classic 2000, but the levels will be screwed up on any modern graphics card and the multiplayer won't work.
You'll notice the enemies here only consist of aliens, praetorians, and predaliens. This is because the shotgun is never actually implemented into the campaign. In theory I could've edited the level files to add it as a pickup, so I could use it against predators and facehuggers, too. But that was so far out of my sight that I just decided to be a shotgun specialist and play all the levels in coop or skirmish mode.
This was recorded on an old 2004 Dell computer, which is also why the framerate (10-15) is so low. I recorded this time with Fraps because the computer rejected the x264 codec that I normally use with Dxtory, and with Fraps I could get the videos files down to a manageable size. Blame old technology for whatever quality criticisms you have.
Music: Serpentor, "All Guns Blazing" (Judas Priest cover, album: Painkiller, 1990).