I have a recommendation for the game. When you play the Atlanteans the mines work faster because 3 miners are working at the same time as well the mine radius is larger. However the Smelting Worker is slow as ever. So for each Copper mine you probably have to build three Smelting Workers to keep up with the miners. I think it would be a good idea to have the possibility to build a fast Smelting Worker (Large House Size) OR expand the current Smelting works building.