that prototype facility in the middle of the map, if your team has control of it, and you have enough money/points, you have to be in the building and bring up the buy screen then click one of the tabs or something and you can pick between 4 weapons: the minigun, the ice gun, something, and the hand-held nuke gun.
Ok, I've been getting glitches while playing this..
like sometimes, some textures look bright yellow with red spots in them... Like walls, backgrounds BEHIND walls that are visible through concrete somehow.. and even the muzzle flash does it sometimes.