Co-Op

Mass Effect 3 is a Role-playing Game (RPG) / Third-Person Shooter hybrid set in a Science Fiction universe. Mass Effect 3 is the third game in the popular Mass Effect series, and is rumored to be the final installment. In it players continue the adventures of Commander Shepard utilizing extreme character customization which is the hallmark feature of the series. Additional features include: the ability to import decisions from both of the previous games into the new game, ownership/play of previous games not required, customizable weapons, improved mobility and melee combat, many returning characters (if they were not killed off in previous imported games), an improved cover system that allows for more action and more.

Nation Red is a fast-paced top-down zombie survival game that supports up to 4 players in co-op mode.

There are 4 character classes available, and players can customise their characters with perks, power-ups, and a variety of weapons.

The game is available from Steam.

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.