In Era of Atlantis, you are a secret society seeking to expand the powerful nations you control during the mythical antediluvian age, 12000 years ago. You have two of these under your control and share each one with a rival. You also have a secondary goal trying to bring “light” or “darkness” to the world. Working with and against your rivals you must prove to be the most powerful secret society in the world before the Era of Atlantis ends either in glory or in cataclysm.
This is an area-control and worker placement game with a unique twist. You control two nations with the lower-valued one counting for your score at game end. This means you will usually try to balance the two. You also share control of each one with another player, who has the same interest in the success of that nation as you do. Switching control of a nation is also possible, but difficult.
There are ways to score a few additional points for yourself only, such as with your remaining mystical energy or by fulfilling secret objectives.
The game is played over a variable number of rounds, with each player taking a turn per round. There are two main ways to gain new areas for your nation: militarily or politically. You can also expand your abilities by constructing buildings or acquiring powerful special actions. A nation will grow more successfully the better its two controlling players can cooperate.
—description from the designer