The most challenging maps for you.

Here, I found a save file. If you set the game settings to slow down the opponent's turn, you can see that the red player simply walked across the water to a small island, which, in theory, shouldn't be accessible, and disembarked. Here's the save file: http://zalil.ru/33850006. I couldn't upload it here; I'm on a business trip, and the internet connection is modem-based, so it seems to be glitching.

And the last Castle is in one place, where all the cities are repositories of keys.

No, I captured it. I opened the save, and I didn't take that Castle in the Dungeon, next to which you get the ability to learn a global spell at level 32.
P.S. Are there any other maps of a similar type?
P.S.S. By the way, has anyone played the map "The Empire of The World II"?