Serious Sam: Double D

Serious Sam: Double D is the first game in the series of three indie titles designed to promote the release of Serious Sam 3: BFE. It is a side-scrolling 2D action shooter with a unique cel-shaded graphic style, reminiscent to that of Weapon of Choice, with surreal enemy designs and limbs being individually animated. It serves to capture the frantic arcade action of Serious Sam: The First Encounter in a 2D format, with dozens of ridiculous enemies spawning at you at rapid rates, having to clear them out with your heavy arsenal of weapons.

In an alternate reality where Sam has killed Mental, General Maxilla revives Mental's dead troops and genetically engineers some of his own in an attempt to take over the Earth. However, Sam won't have any of that and sets out to destroy him and his hordes. Classic enemy types such as Bio-Mechanoids, Beheaded Kamikazes, Rocketeers, Bombers and more have been redrawn in a wacky cel-shaded style. New, absurd enemies include flying chimpanzees and Vuvuzela pancakes. The player roams throughout Egyptian tombs, ancient cities, the Jurassic era and lava temples, annihilating enemy forces one by one. This is intercut with humorous dialogs by Sam and his surgically implanted, sentient AI combat analyzer - NETRICSA, as well as cutscenes where General Maxilla attempts to assemble his aggressive, but dim-witted troops, to no avail.

The main feature of the game is the Gunstacker system, which allows you to stack up to six guns one on top another. It's like making a big tall plate of nachos, only the nachos are guns. Rocket launchers, tommy guns, shotguns and laser rifles can be combined to create a devastating force of firepower that can rip through hordes with ease. There are a total of 18 levels, with various secret passageways and challenges that can be unlocked by finding logo pies of the developer, which pit you against masses of a predominant enemy type at once, with a kill count objective.

The Xbox 360 version is called Serious Sam: Double D: XXL and builds upon the PC version. Differences to the original version include local co-op games for two players where the second player is Huff, several new enemies such as the Torcher Kitty and upgraded opponents such as the Beheaded Rocketeer wearing armor to make it a tougher challenge. Guns can also be upgraded in two ways: as a plain upgrade or for ammo. When choosing ammo the amount of ammo to hold is extended. The plain upgrade changes the gun entirely. The 12 gauge shotgun for instance can be upgraded into the cybernetic bee. It fires bees that lift enemies into the air, making it easier to hit them. The upgrades are bought with money earned by killing enemies. Some of the levels were also reworked to accommodate the changes to the guns. On 21st October 2013 the initial PC version was upgraded for free into the XXL version, importing all the changes from the 360 edition. When launching the game players can choose between the 2011 original version and the 2013 XXL version.