Well, I used only SWAT 4 assets, because I'm not a 3D artist, but yes, it's made by me.
I tried to base it as closely as possible on the blueprints of the SG-1 SGC stage. Obviously I had to make some changes, because the stage is built in a way that makes no sense for a real building (rooms without fourth walls, hallways that go nowhere etc), but the Command Room, Briefing Room, General's Office, Elevator Hallway and Gate Room are all pretty much identical to the show (albeit a bit less pretty). The blast door in front of the Gate Room windows is closed by default but can be opened in game.
I added a ventilation shaft system that is used by SWAT to access the building, gather intel, and pick an entrance route. N.I.D. personell have taken SGC employees hostage during a failed takeover of Stargate Command. A Stargate connection (two-way so you can go back to collect weapons, I couldn't implement dialing) is currently established to an alien world inhabited by humanoids. N.I.D. have taken military equipment to trade with the alien farmers for their supply of rare minerals and diamonds, the value of which is not known to them.
Forces behind this N.I.D. operation had originally planned to take over the SGC diplomatically (as has been tried in the show) to increase the military effort of the Stargate program. For unknown reasons, some SGC personell appear to have opened fire on the N.I.D., prompting a hostage situation on Earth during the ongoing off-world arms deal.
SWAT is in this case more likely to represent an SGC affiliated unit (maybe an Airforce police SWAT unit, or SG-1 itself
) tasked with clearing up this situation and preventing the arms deal.