Lost Atlantis is described by the publisher as a "3X game under the sea". Lost Atlantis is now an underwater exploration game where players gather clues to discover sunken pyramids, defeat their guardians, and collect treasures. The core of the game is a puzzle revealed by compass directions found by players on seafloor tiles. Players use these directions to scour the quadrants of the board for clues to discover pyramids. There is a central portal in the middle of the board that accumulates player scoring tokens as pyramids are claimed, and the game ends when all the central portal spaces are filled up. The player who accumulates the most Victory points throughout the game wins.