Greetings, members of ModDB. My name is Kenny, and I am currently the sole team member of the Zombie Swarm team. I originally started this project in about 2011 with a good friend of mine, but due to neither one of us knowing the first thing about putting together a source mod, it was doomed to fall apart. I had managed to piece together a few scattered scraps of content, but looking back, they weren't really of sufficient quality. Moving on to the present day, I now have much more experience working with the source engine, but I am still something of a novice. Filled with vigour, energy and ambition, I have since resumed work on my abandoned Zombie Swarm project files. At present, my plan is to replace all of the artistic assets and maps in Alien Swarm with novel ones. Essentially, Zombie Swarm will be a re-skinned version of Alien Swarm, with a couple of new missions.
Pump action shotguns have been in use since the 1890s, and so wouldn't look too out of place in the 1950s. The design here is actually a model of shotgun which first saw production in 1996, but the 1996 "super shorty" was in fact based on 1919 designs for "trench shotguns" which never got much further than the prototype stages. One could rationalise that the shotgun seen in the game is one of those prototypes. Besides, I don't think anyone is actually going to scrutinise the shotgun that much that they'll realise the design is from 40 years in the future....
Part of this "stretching of the truth" is required because the non-Vindicator shotgun in Alien Swarm, which this shotgun replaces, wouldn't work very well with a larger pump action or double barrelled design due to magazine size... And I'm not a coder so I can't change the actual stats of the weapon in-game...
Meh, it looks good, and it works fine in-game, so I'm happy with it as it is.... Even if it is a bit of a stretch. ^_^