Accepting map submissions.

Hello everyone. I would like to play a single-player game focused on character development, meaning the map should have only one player without any opponents. The map size should preferably be large or very large. The goal could be to defeat a monster (e.g., 1,000 devils, etc.). I would like to see two treasure chests with artifacts near the castle on the map. P.S. Or, tell me, is there a simple way to modify any map to have only one player?