4C is a RPG toolkit rather than complete game system; it provides a foundation for you to build upon. As presented, 4C is specifically for superhero roleplaying though it could be adapted to other genres with a bit more work.
As a gamer you can use 4C to “build” your own game system or to assist in converting 4C products to similar systems. 4C is not a replacement for any games that you may already own but is, rather, an aid.
You can use 4C as the basis for an entirely new game – strip out the powers and drop in appropriate origins and “classes,”* for example, to create a fantasy game – or as common ground for the development of material that is compatible with other games that use a similar system.
4C is released to the public as public domain and almost every part of the text, including the title, is open for use (the names of those involved in the creation of 4C are not open for use). The copyright on 4C is unassigned and the text is donated to the public domain; anyone can use this material for their own products and with their own ideas.
( * A class could be nothing more than a set package of abilities; by selecting a “class” the character gains specific skills and abilities.)
4C uses “percentile dice”, two differently colored ten-sided dice with one die designated the “tens” die and the other the “ones” die. Whenever the rules state roll d% roll both dice to generate a number between 0 (both dice show “0”) and 99 (both dice show “9”).
Example: Richard rolls d%. The “tens” die comes up 8 and the “ones” die comes up 3, for a roll of 83.
Remember that unlike many other systems, a result of 00 in 4C is 0 rather than 100.