Serious Sam: Double D is out today, marking the first of the indie titles made to promote the upcoming Serious Sam 3: BFE.

The game, created by independent developer Mommy's Best Games, costs $7.99 from Steam, Get Games, Impulse and Direct2Drive and takes the form of a sidescrolling 2D shooter. It's a substantial game in its own right, too, featuring 18 campaign levels across 3 time periods; 25 creatures; 70 secret areas; 12 challenge levels; 30 Steam achievements; "occasional bewbs"; and the enormously entertaining-looking "Gun Stacker" system, allowing you to fire several weapons at once.

"Serious Sam: Double D is digital testosterone -- no lie, my sack dropped a full inch after playing for a couple of hours," said Fork Parker, CFO of publisher Devolver Digital in characteristically brash style. "Quote me, Serious Sam: Double D will knock your ass through puberty all over again."

With a glowing recommendation like that, how can you possibly refuse? Find out more about the game and get links to its various online distributors via the official website.