The map has been updated to version 1.1. The Overlord and Astral Gate have been removed from the map, and the Demon Dungeon has been made more challenging and richer. Now, you can not only develop the Gnome and seal the Demon Portal, but also normally develop the Demon and prevent the Gnomes from breaking the portal.
Thank you to everyone who pointed out the shortcomings of the map!
I liked this version of the map (1.1) more than the original. During the game, I managed to develop the Demon to level 33!