All three of my last attempts resulted in this:
Day 1 - landing
Day 1 - capturing the main Fortress and immediately capturing all the others (in the final version, I was 2 squares short of capturing the Barbarian Fortress)
Day 1 - destroying the messengers

I wonder how long it took you to sail there ;) Mine:
Day 1 - landing
Day 1 - sailing
Day 1 - landing
Day 1 - everyone is doomed :) For this, I even had to finish building the Magic Portal in the Barbarian Fortress, and the Mage Fortress remained without a Magic Portal, but I got lucky :)

Wow, I didn't know that! Now I understand why it refused to finish building the tower. I raise the nearest sulfur mine at the very end.
Just a small correction: in the first game, I think the maximum is 4 floors. Back then, they didn't know how to build skyscrapers yet. :)

I should have analyzed the results of the first tournament for the first game. I paid attention to the glitches with building construction in the computer's Fortresses. This time, even if by chance, I figured it out :) And yet, during the first playthrough, Magic was built in only two out of three Fortresses, and in the final version, it was built in only one, and I had to finish building it in one of the Fortresses myself. That's it.