It has 16 player co-op. 16 PLAYER CO-OP. It also has dedicated server files available, so you can set up your own server however you like.

I would strongly recommend skipping the first 4 levels, though. The game takes a while to warm up, and it doesn't really get Serious until you get the rocket launcher. Level 5 also starts out with a gratuitous boob shot, which is fun for the whole family.

I would watch this madness. 16 player co-op in Left 4 Dead was always a blast, this surely has to be just as good.

I would thoroughly enjoy a Serious Sam BFE TNT, especially with Brad at the wheel.