Play against a human.

A duel isn't proof of anything at all, especially when we're talking about a multiplayer game on a map. On a map, you can't build all the creature dwellings in a castle at the same time (I usually have 2-3 built maximum by the time I face another player). And there aren't enough resources for everything. And heroes don't reach level 30 (if they even reach 15, that's good). And the unique buildings of cities function. And there are many other things...