Like not one map, include ancient age , medieval, renaissance and maybe a mod where all players fight against one emperor who almost conquered the world (like previous Genghis khan or British empire) and whoever damaged most will be getting more rewards.
Or maybe alternating army power of countries in each maps
Make more maps in battle royale and selection of countries not depending on one bidd, like if there is bidding options whoever bids most will get best one and rest follows, but not each country