That looks like the Quake Mod Tremulous before it's standalone days?
Oh, a Turret, that's Niveus! That's the Lamer Spot off the stairs. That's Tremulous before standalone afaik.
On the HUD note, that's a pretty hawt hud. There was a pretty attractive model for the marine there too. Personally, although I've only seen screenies, the original before standalone Tremulous looks a lot more Tremulous. Darker textures, wicked marine model. Made it look like aliens actually had infested space stations and such. We should petition to bring back ye olde Tremulous!