In a distant future, scientists were able to build small alternate Earths. Exactly 504 such Earths have thus far been built. The scientists programmed each of these Worlds with an individual set of laws and rules which the residents strictly follow and consider most important for their lives. These may be exploration, consumption, economics, military, etc., and each is unique. You can visit all of these 504 alternate Earths to experience how the people are living, and decide which of these worlds harbors the best civilization. On which World do you want to live? Explore them all and decide!
Since 504 is so new there aren't any reviews of it yet, but why not check out this article about it to get some more infomation.