I used Petra AI on all difficulties. Made both starting locations bigger, and included more starting resources (bushes). Using the developer overlay is very helpful, but unfortunately the pop-up notifications don't seem to indicate any errors relating to the AI not attacking; AI has enough resources, workers, soldiers, and buildings..., yet is still unable to attack. The Dev overlay does show errors--like telling me that a building can't be built-- but the AI seems to resolve these issues on its own, since they end up successfully building them elsewhere. I can play a match from both locations without any errors, so it appears this is only an AI issue. Perhaps this will be fixed in the next version? Currently running alpha 16.