Hollow World

Created in 1990 by TSR as a campaign setting for the Dungeons and Dragons game, the Hollow World detailed the inner world of Mystara.

The Hollow World was originally discovered by Ka the Preserver, an ancient Immortal who began life as a giant carnosaur, who after finding it, decided to use the inner surface of the world as a refuge and preserve for creatures that were on the verge of becoming extinct in the ever-changing outerworld.