My wife just gave me the game for a belated birthday present(as I spent my BDay in Afghanistan), and although I haven't started a SP game yet as I'm still majorly jet lagged, I did check out the credits. It seems that the test group was very small compared to the Civ4 expansions, and although I don't know how large an internal test team there was, the logical conclusion is that not only would the MP testing have been limited but testing of all aspects of the game would have be more limited than was done with the Civ4 XP's, so it's not a surprise that there are going to be bugs and balance issues especially since bugs are easier to fine but game balance is time intensive to get right.
CS
CS
Comment