I enabled a three mods and played. The mods: 0 A.D., Millennium A.D. and the formation fighting mod. I saved the game. Then I restarted the game and tried to load my saved game. The filter did not show me my saved game. I had the option to disable the filter. Selected my game and got a warning, saying that my mod selection is incompatible. The only difference the first and second time was the order in which I selected and activated the mods. The first time: 0 A.D., Millennium A.D. and the formation fighting mod. The second time: 0 A.D., the formation fighting mod and Millennium A.D. As you can