Co-Op

Guns of Icarus Online is an online multi-player FPS. The game is set in a steampunk world where players take on one of three roles on a dirigible (airship). The roles are gunner, mechanic and captain. Players fire guns on the dirigible, attempting to shoot down their opponent's ships. Matches are in teams of 3-4 ships per side (red vs. blue). Players mount the large guns and pilot them from a first person perspective. They can also repair damaged guns and ship components.

Trapped Dead is a tactical real time strategy game. Players control their characters in a 3rd person isometric view through a mature Zombie survival scenario inspired by the successful Horror movies of the early 80s.

Blast your way through historic Mars with a crack team of up to 4 friends. Marvel and rejoice at vast expanses of lovingly handcrafted pixels. Brave the hostile Martian frontier armed with 1619’s finest steam-punk weaponry. Master innovative co-op mechanics paired with classical top-down shooter gameplay. Climb the online leaderboards in single-player classic arcade mode.

Bunch of Heroes is a humorous 4 player cooperative top-down shooter for Windows through Steam. The game has online co-op with up to 4 players.

The Bunch, is the most formidable team of fighters from different parts of the world ever assembled. In the game the Earth is under attack, An Alien Invasion is threatening all of humankind, with no regard to gender, color or nationality. And these nasty Aliens have a powerful Zombie Army.

Age of Empires Online (abbreviated AoEO), is a history-based RTS. The game is free-to-play—it is free for users to play, with the additional option of earning or purchasing premium content. Premium content may include access to many special items and blueprints, and more quests and features. Also, booster packs are now available, such as Defense of Crete and Skirmish. This former gives the player the ability to play in a survival type mode game, while the latter allows up to four humans versus up to four CPU opponents in a more traditional skirmish gamemode. (Soure: Wikipedia)

Alien Breed 2: Assault, like Evolution, is an isometric shooter set on board a futuristic spacecraft. In each level, the main character Conrad is given a series of tasks such as collecting key cards, restoring power, or escorting innocents, which he must complete before finding that level's exit. Standing in his way are a variety of aliens who will attack him, usually en masse. He can also suffer damage from explosions, fires, electrical disturbances, and enemy turrets. Conrad can run and shoot in all directions, and can collect a number of different weapons and items to aid him.