Similar to previous games in the series, the player takes on the role of various characters during a single-player campaign. The characters' involvement in the plot occurs simultaneously and overlaps the events in the game. As such, the player's perspective can change from one character to another between missions.
After completing the campaign, a special epilogue mission is unlocked for play. The mission itself talks about Soap taking over Price's position as Captain and the epilogue mission is his first ever mission during his time as captain. After the whole mission, the player will see a photograph with Price, Gaz, Vasquez and Griggs in it. On it will be written, "Heart breakers and life savers. Thanks for playing." This may mean that Price too, died during the road chase.
Each mission features a series of objectives; the player is led to each objective with the HUD, which marks its direction and distance. Some objectives require that the player arrives at a checkpoint, while other objectives require the player to eliminate enemies in a specified location, stand their ground to defend an objective, or plant explosive charges on an enemy installation. The player is often accompanied by friendly troops, who cannot be issued orders. Laptop computers containing enemy intelligence appear throughout the campaign, and can be collected to unlock game bonuses.
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