The campaign

Modern Warfare 4's campaign runs three acts across 16 missions. Finishing it unlocks campaign rewards for multiplayer and the completion achievements, so it's worth clearing even if multiplayer is the part you came for.

The difficulty settings

Recruit and Regular are for the story. Hardened pushes harder, and Veteran and Realism are the long, punishing runs. In past Call of Duty campaigns the hardest settings have carried their own achievements.

What's included

The full campaign covers every mission across all three acts; a single mission covers just that one, on the difficulty you pick. Campaign progress, unlocks and achievements earned on the run stay on your account.