What Did I Do to Deserve This, My Lord?!

Background

My Lord, your objective is simple. Please create a powerful dungeon to protect me from the dreadful heroes and warriors looting our home. Humans are powerful with their skills and magic, but if we could create a perfect ecosystem of monsters and beasts, we can defeat them!

As the video game boss you stand to be every obstacle for heroes intruding monster territory. Your goal is simple create a vast dungeon filled with monsters and ghosts. The dungeon however, must be a self sustaining ecosystem. No monster or ghosts shall over populate each other or the dungeon will destroy itself before the humans arrive. You can make a elaborate scheme of mazes but if there is no one to protect the place you will be screwed.