Challengers is a complete superhero role-playing game, featuring revised and updated mechanics derived from To Challenge Tomorrow, with rules for running an innovative superhero campaign, with over 100 powers, six adventures and dozens of villains. Challengers is a very flexible superhero system ideally suited to play with low-power characters.
From the introduction:
The general rule system for Challengers can be used in any superhero campaign background with any orientation or level of power . As an Introduction to the system and the alternatives possible for superhero role-playing, this book provides an introduction to the original "Challengers" campaign set In the possible future of our own world just a dozen years from now.