Successfully complete the indicated task to unlock the corresponding armor. Story mode missions unlock One Man Army missions. One Man Army missions will unlock specific armor for the One Man Army missions and completed missions in Mission Archive mode.

Classic: Successfully complete the "One Man Army vs. Mercs" challenge, which is unlocked after Story mode mission 7 (Arctic Battle).

Classic Mark I: Successfully complete the "One Man Army vs. AIM" challenge, which is unlocked after Story mode mission 8 (Lost Destroyer).

Extremis: Successfully complete the "One Man Army vs. Maggia" challenge, which is unlocked after Story mode mission 4 (Maggia Factories). Extremis is capable of stealth. It has a shockwave attack in place of grenades and missiles. It is very efficient and powerful.

Hulkbuster: Successfully complete the "One Man Army vs. AIM-X" challenge, which is unlocked after Story mode mission AIM-X, where you must destroy four power couplings before any are repaired, then defeat Horgan and his giant cannon. Hulkbuster is slow but can sustain massive amounts of damage. Its Repulsors are more like cannon shots, and in place of grenades and missiles is a single cannon shot that hits a target, then a moment later creates an explosive shockwave. It is perfect for groups of enemies.

Mark II: Successfully complete the "One Man Army vs. Ten Rings" challenge, which is unlocked after Story mode mission 3 (Stark Weapons).

Ultimate: Successfully complete the game. The Ultimate armor is the equivalent of the Extremis but does not have stealth, has a more powerful Unibeam, and Gatling Repulsors that are weaker but acceptable.