Co-Op

Two hands to hold guns plus a pair of piranha-headed tentacles: use all the deadly tools at your disposal to kill with gruesome variety, and score big to unlock new skills and bonuses.

The Second Encounter starts where the previous game left off, with Sam travelling to Sirius on the "SSS Centerprise". Unfortunately the starship is accidentally hit by the "Croteam crate-bus" and plummets down to Earth's surface. As the starship falls, Sam reads the coordinates and frets about crash-landing into Egypt again, but instead he crashes into Central America in the Mayan age, with the starship now heavily damaged upon impact.

Killing Floor is a Co-op Survival Horror FPS set in the devastated cities and countryside of England after a series of cloning experiments for the military goes horribly wrong. You and your friends are members of the military dropped into these locations with a simple mission: Survive long enough to cleanse the area of the failed experiments!

Dota 2 is a Multiplayer Online Battle Arena (MOBA) game from Valve running on an updated version of the Source engine. The game was released on July 9, 2013 for Microsoft Windows, OS X and Linux versions of Dota 2 were released on July 18, 2013.

Although Garry's Mod is usually considered to be a full game, it has no game objective and players can use the game's set of tools for any purpose. Garry's Mod allows players to manipulate "props" – various objects that players can place in-game. Props can be selected from any installed Source engine game or from a community created collection. The game features two "guns" – Physics Gun and Tool Gun for manipulating objects. The Physics Gun allows objects to be picked up, adjusted and frozen in place.

Black Ops is a first-person shooter, retaining the same gameplay mechanics as previous Call of Duty titles. The player assumes the role of a foot soldier who can wield various firearms (only two of which can be carried at once), throw grenades and other explosives, and use other equipment as weapons. A player close enough to an enemy can kill with one knife blow. A character can take three stances: standing, crouching or prone. Each affects rate of movement, accuracy, and stealth.