I have a few suggestions myself. First, it would be good to have walls be cheaper since they are rarely effective at the moment. If players would like their wall turrets firing arrows and potentially ballista shots later, that should be an upgrade. Having walls cost hundreds of stone is ridiculous balance-wise and Age of Kings recognised this problem. Next, archers generally should not be as effective as they are. Historically they were actually nothing that decisive in most battles and their role should most likely be limited to supporting infantry. Persia also is depicted having very good archers, but I see no historical basis for that. If there is any bonus they should have, it should be in rapid deployment. Third, blacksmith upgrades should not be generalised with melee infantry upgrades being with ranged as it makes little logical sense. For that matter, having them cost food seems obscure to say the least. With food there may as well be stone added.