Planes alone are a bit broken and OP. Reasons: They have an insane attack range. You can even build airstrips in the front to push the attack range even further, though its rarely necessary. They don't take damage when attacking unless there is anti-air, a jet fighter, or a death robot in the vicinity It only costs 190 gold to upgrade a bomber to a jet bomber (It costs more than 1,000 to do some other upgrades to your army units. This is insanely cheap by comparison. Add to planes, the fact that a level 4 rocket artillery with a drone can shoot from 5 tiles away, and you are untouchable. The AI places their cities so close together and builds so many encampments that when advancing across enemy territory you can literally keep all your units safe from harm. One rocket artillery with a drone in a city. Another rocket artillery with a drone in an encampment. Maybe another rocket artillery one tile behind the city or encampment and still impacted by the drone. Then you have a few planes (or really as many as you can with your available aluminium). Plus, the drones give vision, so you don't even need a spotter melee front line unit like you used to. All that together and you are shooting cities when they likely can't even tell what is hitting them. They probably can't see my rocket artillery because its so far away. They definitely can't see where my planes are coming from because they are very far away. (Unless they have spies.) Yeah, the AI should be building anti air and jet fighters, but they don't build much of either. And even then, that only helps them against the planes. What do they do about my rocket artillery that is whittling down their defenses while hiding in cities and encampments? I've never had to play against this strategy, but I don't know how you would defend against it. Late game, a few planes, a few rocket artillery, a drone or two, and a single helicopter or tank to take the city when it reaches 0 are all you need. It's a little crazy. I don't know what the fix is, but this is very broken IMO.