Editing Cooperative play

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[[File:Halo 3 - Cooperative.jpg|300px|thumb|right|The four playable characters in ''[[Halo 3]]'''s Co-op mode, from left to right: [[Usze ‘Taham|Usze 'Taham]], Arbiter [[Thel 'Vadam]], Master Chief [[John-117]], and [[N’tho ‘Sraom|N'tho 'Sraom]].]]

'''Co-op''' is a [[multiplayer]] gametype found in all ''[[Halo universe|Halo]]'' games except ''[[Halo PC]]'' and ''[[Halo 2 Vista|Halo 2 PC]]''. It allows two or more people to play the [[Campaign]] together.  

Co-op is also available in the ''[[Halo Wars]]'' campaign, both via system link and over Xbox LIVE. However, unlike in other Halo games where co-op is available, it is not possible to play local co-op in ''Halo Wars''.

Co-op gameplay basically involves two or more people playing through the campaign as a team. If one player dies, they can come back to life, or "respawn". The player who dies has to wait until the player(s) who is/are still alive is/are not engaged in combat and is/are at a safe location before they are able to respawn. If all players are killed, they will restart at the last saved checkpoint. Additionally, in ''[[Halo 2]]'', if two players are playing on [[Legendary]] difficulty and ''either'' of them die, then both of them have to start at the last checkpoint. In any of the other ''Halo'' games, nearly all players will attempt [[Legendary]] on co-op, because Legendary is often too difficult to attempt alone. When a player respawns in ''Halo: Combat Evolved'', they are always equipped with an [[MA5B Individual Combat Weapon System|Assault Rifle]] and a [[Type-25 Directed Energy Pistol|Plasma Pistol]]. In the sequels, each level has a designated pair of weapons that respawning characters start with.

===Halo: Combat Evolved and Halo 2===

In ''Halo: Combat Evolved'' and ''Halo 2'' co-op, when playing a level involving the [[John-117|Master Chief]], both players will control two identical copies of the Chief; when playing a ''Halo 2'' level involving the [[Thel 'Vadam|Arbiter]], both players will control identical Arbiters. ''Halo 2'' was planned for online co-op mode for up to two players on Xbox Live, but due to time constraints Bungie was not able to perfect online co-op for ''Halo 2'', the user interface still contains clues as to how ''Halo 2'' would have had co-operative game mode, and it's even more apparent modders were able to activate this game mode.

===Halo 3===

In ''Halo 3'', when there are two players, player one plays as the Master Chief and player two controls the Arbiter. Certain cutscenes and lines of dialogue are altered to reflect the fact that, unlike in the single player mode, the Arbiter never leaves the Chief's side. In addition, all of the Arbiter's lines of dialogue outside of cutscenes are removed. In three or four player co-op, player three controls [[N’tho ‘Sraom|N’tho 'Sraom]] and player four becomes [[Usze ‘Taham|Usze 'Taham]], though these characters do not appear in cutscenes, and are not referred to in dialogue. Player one, as the Master Chief, begins each level and respawns after dying with human weaponry such as the [[MA5C Individual Combat Weapon System|Assault Rifle]] and [[M6G Personal Defense Weapon System|Pistol]], while the other players, as Elites, begin levels and respawn with Covenant weaponry such as [[Type-51 Carbine|Covenant Carbines]] and [[Type-25 Directed Energy Rifle|Plasma Rifles]]. Two player co-op can be played in split-screen mode in all three primary ''Halo'' games, but three or four player co-op in ''Halo 3'' is only available over system link or [[Xbox LIVE|Xbox Live]], with at least two Xboxes with two players on each.

===Halo 3: ODST===

Co-op is also available in ''[[Halo 3: ODST]]''; in the [[Mombasa Streets]] sections of the campaign, when player one controls [[the Rookie]], player two controls an identical [[Orbital Drop Shock Trooper|ODST]]. During flashback missions, player one controls the main character of the flashback, but player two still controls a generic ODST, even if the flashback character is accompanied by other members of [[unidentified Shock Trooper squad|the squad]]. For example, in [[NMPD HQ (level)|NMPD HQ]], the flashback is from the perspective of [[Kojo Agu|Romeo]], who is constantly accompanied by [[Edward Buck|Buck]]. In co-op mode, player one controls Romeo, but player two controls a nameless ODST, leaving Buck as an NPC. The same goes for players three and four. Just as in ''Halo 3'', two players can play on one Xbox with split-screen, but up to four players can play at once via Xbox Live or system link.

In gameplay terms, each player can access the map and drop their own waypoint, which will show up on everyone's map, but only on the compass of the player who placed it. In addition, all players download all [[Audio log|Audio Logs]], no matter who actually accesses the terminals. Only one log can play at a time, and any player can stop the playback or start the playback of a different log.

Finally, ''ODST'' adds a new co-op multiplayer gametype called [[Firefight]], in which players are allowed to pick their character, choose their personal emblem, and decide whether or not their character is wearing their helmet (with the exceptions of the Rookie, who must wear his helmet, and of [[Avery Junior Johnson|Johnson]], who cannot wear one). For more details on Firefight, see its main article.

''[[Halo: Reach]]'', like its predecessors, has full co-op features, but unlike the previous games, no player's appearance is set. Each player can extensively customize the appearance of [[SPARTAN-B312|Noble Six]] in Campaign mode, and this appearance is applied to their character in co-op as well. No changes are made to Campaign dialogue to reflect the fact that there are up to ''four'' "Noble Sixes".  

When playing co-op through System Link or Xbox LIVE, each player can see their own version of Noble Six in cutscenes. During split-screen co-op, cutscenes are depicted by the player one version of Noble Six. However, if player one signs out from the Xbox 360, then logs back in, then player two's version of Noble Six will appear in the cutscene instead.

===Differences===

Co-op gameplay is very different from single-player gameplay; there are several new strategies and alterations present. Starting and respawn weapons tend to vary between single-player and co-op, as do the starting weapons of each character and the strategies that can be used in co-op—some of which are documented below.

The "coward method" is basically having one player hide in a safe spot while the other player charges forward and kills everything with impunity, charging again and again as they die until no opposition remains. This method of progressing is generally frowned upon in the community, but it is still commonly used to beat the campaigns on Legendary. It cannot be used in ''Halo 2'' on Legendary, however, as if one player dies, both must restart from a checkpoint.  

This method can also be used by one person playing as two characters on co-op, provided that they can place the "coward" in a safe, unreachable place.

In many ways, it is very much the same as the "cannon fodder galore" strategy, in which the "brave person" throws enough of themself at the enemy until they go down. Whilst not the most creative or innovative idea, it is still a valid strategy just not a very ''good'' one.

===Full Shotgun===

This method involves all players charging at the enemy. This method is rather foolhardy, and much more difficult than standard play. To use this technique successfully, players will need to coordinate movements with each other to avoid wounding or killing each other with splash damage or friendly fire.

===Run and Gun===

This ''Halo 3''-specific method consists of attempting to get through the level as quickly as possible, while also trying to get the most [[Campaign Scoring|points]] possible. It often involves using vehicles and ignoring many enemies that the player may otherwise be inclined to shoot. The reason players do this is generally because they want the Legendary symbol for their service record; they may also wish to get the [[Campaign Scoring#Achievements|meta-game achievements]] by relying mainly on the time bonus for the level.

===Combat Roles===

This method makes up for the 2 or 3 weapon limit and has players focus on specific aspects of combat, such as enemy types or positioning. One of the most ideal strategies utilizes one of the players using weapons less resistant to [[energy shielding|shielding]] while another player uses weapons less resilient to non-shielded enemies. This way, shielded enemies would lose their shielding rather quickly and become vulnerable to the other player who would have the proper weapon equipped to finish off the enemy, effectively removing the need to constantly switch weapons. Ideally, the player assigned to shielded enemies would utilize [[Type-25 Directed Energy Pistol|Plasma Pistols]] for their overcharged shot while the player assigned to take out the non-shielded enemy would utilize headshot weapons, namely a [[Battle rifle|Battle Rifle]] or [[Type-51 Carbine|Covenant Carbine]], forming a two person [[Noob Combo]].

===Two-Way Attack===

Plan is simple: one player attack the enemy from the front, whilst the other player goes round and either flanks the enemy from behind or attack them from the side. Can be used against the more powerful Covenant (Brute Chieftains, Zealots, Ultra Elites, Mgalekgolo etc) in which two or more players would gang up to take a powerful enemy down or, can be used to eliminate large groups of Covenant using combined Assault or Battle Rifle fire.

Alternatively, two players may not be needed for this method. It can be done using the UNSC Marines as a distraction for the Covenant whilst the lone player attacks from the side (or flanks). One example of this strategy actually being ''used'' is in the level "Tarazi Plaza" in Halo 3 ODST, Australian marine Chips Dubbo suggests to Buck "flank the Covenant on the streets" whilst Dubbo and his team-mate distract the Brutes.

==Gradual Fragmentation==

Gradual fragmentation is the method of taking out enemy units one at a time, or taking out individual enemies one-by-one  either by grinding them all down gradually (hence the name "Gradual Fragmentation") or using marksmanship to snipe enemies out one after the other. ''Can'' be done on single-player but much more efficient on co-operative play.

==See also==

*[[Campaign|Campaign Mode]]

*''[[Halo: Combat Evolved]]''

*''[[Halo 2]]''

*''[[Halo 3]]''

*''[[Halo Wars]]''

*''[[Halo 3: ODST]]''

*''[[Halo: Reach]]''