This mod causes tech advancement to stop at a certain era by disabling the next era's techs. There are 5 different mods for each stopping era. I recommend further editing the tech tree for more "playability." Some examples: cannons are made available by steel, which is an industrial tech (which also makes Ironclads available), but cannons would be nice to have in the Renaissance age, so you might want to change this. Also, galleons aren't available until the Renaissance, so conquering across ocean with the Medieval mod won't happen unless you edit things. Classical Era Directionslace each of the 5 folders (Era Stop Ancient, Era Stop Classical, Era Stop Medieval, Era Stop Renaissance, Era Stop Industrial) in the Mods folder.