From the introduction:
Welcome to Barsoom, the first and most famous of the worlds created by Edgar Rice Burroughs. These pages are dedicated to any roleplayers who, having read about John Carter's exploits on Mars, have wished they could join him.
Heroes of Mars is an adaptation of the setting created by Edgar Rice Burroughs, centered on a FUDGE mechanic. The setting is presented in six major HTML pages: Introduction, The World, Empires and Cities, Characters, Adventures, and New Rules. Note that some of the material is hosted at other sites and is incorporated by reference.