Challenges are levels in Strike Force Heroes. They are not chronologically tied with the campaign, but they are simply extra missions.
Challenges are the levels you should play if you really want to earn exp and level up. They are hard and most of them have a lot of extras such as: In Norris Chuck the mod is tin man mod and the enemies die in 1 hit and you have 700 hp. This might have been inspired by "Chuck Norris Facts".
- Chuck Norris once killed 25 men with just a butter knife.