Play Modern Warfare 4's campaign on Regular if you want the story, and Veteran if you want the challenge and the Veteran Completer calling card in one run. Realism unlocks after your first finish, and YOLO only after Realism. The completion rewards are the same on every difficulty.
That last point is the one most players miss. The eight Operators, the tokens and the cosmetics don't care how hard you played; only the Elite calling card sets do. Checked against Activision's Campaign Early Access and Ready for Launch posts, plus notes from early access players.
The Realism and YOLO rows come from early access players, not Activision. They describe YOLO the same way: die once, or fail an objective, and you're sent back to the first mission, Mayhem, whatever mission you were on.
Finishing missions pays out sixteen rewards in a fixed order, and Activision's list ties none of them to difficulty:
Activision's Elite Campaign Mastery category has three Mastery Sets: Veteran Completer, Realism Completer and YOLO Completer. They're the only campaign rewards tied to how hard you played, and finishing every challenge in a set pays an animated Mastery Calling Card.
You can change difficulty from the pause menu during the campaign. Early access guides warn it can affect achievements tied to that difficulty, so if you're after a card, stick with one setting from start to finish.
Do I have to finish on Veteran to unlock Realism?
No. Finishing the campaign on any difficulty, Recruit included, unlocks Realism. Only YOLO needs a specific run, and that's Realism.
How long is the MW4 campaign?
Sixteen missions. Players who finished it in early access put a first run at around eight to nine hours on the default difficulty. Veteran and Realism take longer.
Do campaign rewards work in DMZ?
Yes. Activision says every completion reward carries into multiplayer and DMZ at launch, including the eight Operators and the five tokens.
