Fun at first, then unplayable. After reaching a certain point the AI becomes OP to the point you can't even expand past your start city before you are overcome by unsurmountable odds from AI players. The AI does not adhere to the same rules of engagement or the growth rates that the game forces upon the player. The player starts every game with 20 coins whereas the AI clearly has an infinite supply. Also, special units are rare and powerful, but the AI players spawn them exclusively. Spend big.