Predictably impossible
The problem with this game is that the AI clearly has access to raw numbers, while you don’t. The AI will attack the weakest/nearest opponent - and if that happens to be you then you get gamed up on and you are screwed. The game shifts the balance for or against you by putting you in advantageous or disadvantageous starting positions on each map. So some maps are easy because you can ramp production up while the two AIs weaken each other. Some maps are impossible because the AIs surround you and wear you down until you can’t keep up your production and collapse. So, it’s fun, but inherently balanced against you in later maps. It seems that the only way to win is to keep restarting the map until the AI decide to attack each other and not you, so you can divide and conquer.