Man, mapping for Alien Swarm is messing with my head.
Everything I've spent years learning in terms of optimisation and scale is being turned on its head.
All world geometry is converted to func_detail during the compiling process so you have to make a massive box around the map (SHOCK) and tie it to an entity in order for it to not be tied to an entity upon compile.
Walls are ~160 high (HORROR)
i need to lie down.