The database, a SteamKit2-powered tool providing more information on individual game files in Steam's database, shows two files for Windows PC at the bottom of the files list: "Expansion — One World Content" and the "One World" executable file. The files list no additional information.
The last major expansion released for Civilization 5 was Gods and Kings last June. Publisher 2K Games and developer Firaxis have not announced any planned future expansions for the title.
When contacted for comment, a representative for 2K Games told Polygon that it is company policy to not comment on rumors or speculation.