Do a simple test: Start up any campaign in M2TW on VH/VH and simply press next turn button for max 10 turns. Chances are pretty good that you will be attacked or sieged in 5 turns depending on faction you chose. Repeat same experiment on same difficulty with retrofit. I tried 5 different factions for 20 turns and nothing: happened AI was passive against me. Which explains why I was able to expand so easily when I played the mod. That is not total war that is dumbed down easy mode for the masses if you ask me. If I choose VH campaign difficulty then I expect the Mars people land and attack me never mind my neighbours.