4-Player Co-op Glitch, Halo Alpha

The 4-Player Co-op Glitch in Halo 3 and Halo: Reach allows three or four players to play locally in Campaign or Firefight. Have two players sign in and proceed to the Campaign or Firefight lobby. While in a Campaign mission or a Firefight game, press A for the amount of players that are going to join. Quit the current mission/game. Start the game again, but this time press A for the third player a second after the final beep of the countdown. For 4 players, do the same, but press A for the fourt

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