The Ironbro campaign is different from the primary campaign in a bunch of game-changing ways. The first is the most notable: Each bro only has one life. If they die, they stay dead. They cannot be brought back to life by any means, including restarting the level. It is possible to avoid dying by pausing the game and restarting the instant before you are hit, although this takes godlike reaction times and is fairly impossible for anything other than falling into a rather long pit. The second feature is the unlock system: You start with a random bro and unlock the rest as you save POWs. It is possible and quite easy to fail the entire campaign because you didnt unlock any other bros and died. A single MISSION FAILED results in expulsion from the campaign. Lives also carry through from level to level and zone to zone: You cannot fail a mission unless you lose all your lives. You can have a maximum of 30 lives, (One for each bro). Once you reach 30 you will never see another POW and can only lose bros from that moment on. Make sure to rescue as many POWs as possible, but don't go for it if it might put your current bro at risk. It is not worth losing a bro to gain one back when you could safely get one later. Dying during the campaign has the same results as dying with more than 1 life in arcade and normal campaign: You respawn at the last activated checkpoint and all the Mooks stop shooting randomly. Remember: The less deaths, the better.