Unlocking Iron Man's different armors
     Clear the game on easy mode to unlock all armors.

Unlockable:         How to Unlock:

Mark I Armor        Complete First Mission

Mark II Armor       Complete Second Mission

Mark III Armor      Complete Fourth Mission

Classic Armor       Complete Sixth Mission

Classic Red 
and Gold Armor      Complete Ninth Mission

Stealth Armor       Complete Eleventh Mission

Titanium Man        Clear Game on any Difficulty Setting