[friagram]

just make a map that is 1 model, and put that in the skybox, set it as a prop_static and you're set
also, you really should make translucent sprites for the laser thingies (use additive mode so it simulates light blending).
Should also be some kind of hit indicator, or explosion when something hits.
You could probably do this with tempent particles.
I know you can parent tempents to entities, but it can be a bit buggy. Mabye worth a shot, I think the limit of tempents is something like 400 drawing at the same time or something...