Cooperative gameplay (often abbreviated as co-op gaming) is a feature in video games that allows players to work together as teammates against one or more AI opponents. It is distinct from other multiplayer modes, such as competitive multiplayer modes like player versus player or deathmatch. Playing simultaneously allows players to assist one another in many ways: passing weapons or items, healing, providing covering fire in a firefight, and performing cooperative maneuvers such as boosting a teammate up and over obstacles.
In its most simple form, cooperative gameplay modifies the single player mode of a game, allowing additional players, and increasing the difficulty level to compensate for the additional players. More complex examples exist, however, with broader modifications to the story and gameplay. Some co-op games include a new ending when completed in co-op mode. This new ending is unlocked only when players work as a team to complete the game. For instance, ''Bubble Bobble'' features an ending that can only be accessed when two players survive co-op mode, as do some console beat 'em up games such as ''Double Dragon'', ''Streets of Rage'', and ''Die Hard Arcade''.
Co-op gaming can operate either locally—with players sharing input devices or using multiple controllers connected to a single console—or over a network, with co-op players joining an existing game running on a game server via a local area networks or wide area networks. Due to the complexity of video game coding, co-op games rarely allow network players and local players to mix. Exceptions do exist, however, such as ''Mario Kart Wii'' or ''Call of Duty Black Ops'', which allows two players from the same console to play with others online.
Co-op gameplay has been gaining popularity in video games in recent years, as controller and networking technology has developed. On PCs and consoles, cooperative games have become increasingly common, and many genres of game—including shooter games, sports games, real-time strategy games, and massively multiplayer online games—include co-op modes.
Co-op gaming can also exist in single player format, where the player works alongside his or her previous plays in order to complete an objective.
==History of arcade co-op gaming==
Atari, Inc.'s '1978 coin-op ''Fire Truck'' is widely believed to be the first arcade coin-op to feature co-op play. As its title suggests the game involves a large fire truck, and in two-player mode both players are required to cooperatively steer the vehicle along a winding road, with one driving and steering the tractor of the truck and the other steering the tiller for the rear wheels, controlling the swing of the trailer.
Several early 80s arcade coin-op games allowed for co=op play, but typically as an option. ''Wizard of Wor'' offered solo, competitive two-player, or cooperative two-player gaming., while Williams Electronics' ''Joust'' encouraged players to alternatively compete and cooperate by awarding bonus points for co-op play in some rounds (Survival Waves) while alternatively awarding bonuses for attacking the other player (Gladiator Waves). Two-player games of Nintendo's ''Mario Bros.'' could be played as competitively or cooperatively depending on the players' whims.
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