@SO, Please reconsider and do some more study on it,Please.
I've been dealing with this in keldath's Barsoom mod. Basically it spawns a Stack of barb units in your 1st 9 tiles of your city. They are generally better units than what you have available. They are also immobile for 2 turns then they attack. But because they can spawn very early in the game (starting with turn 2) if not properly implemented will wipe you out before you have time to build your 1st defensive unit. Game over before it starts.
JosEPh