Above is reprinted, in its entirety, the strategy guide for Serious Sam 3, which comes out next week and includes 16-player co-op for the campaign mode. Forward the guide to 15 friends with whom you might be playing so that you're all on the same page..
Serious Sam lets you carry around a dozen different weapons at once, and figuring out which weapon to use against which enemy, and managing your ammo between refills requires more strategic thinking than most modern single-player FPS games.