Rich Knuckles is back with a retrospective looking at the Serious Sam series since its inception in 1996. Why is he doing that? Because the game is part of this week's Humble Bundle where you can get almost EVERY Serious Sam game ever created including the Indie game series games for a price you name.
Here's the list of what's included:
Serious Sam Double D
Serious Sam Kamikaze Attack
Serious Sam: The Random Encounter
Serious Sam Public Test 2
The sale ends on June 13th. Most games are available on PC via Steam, some games require Steam. All of the linked games above support cooperative play.