From the back of the core rulebook:
"Atlantis: The Second Age is a complete and comprehensive setting that uses the Omni Role-Playing Game System, but can easily be adapted to most popular fantasy roleplaying games. Within, you will find all you need to run a campaign in the legendary Second Age of Atlantis, including an Atlas of Antediluvian Earth, regional maps, city maps and guides and a compendium of creatures, races, animals and various pantheons of deities. Set in the mythic past of our own world, players can take on the roles of Atlantean Alchemists, Khem Priests of Ra, Khitan Astrologers, Hesperian Amazon warriors, Satyr bandits, Goblin assassins and a near limitless variety of other character types."