Here’s an idea: gameplay sort of like Goblin Cleanup, you have various chores you have to do cleaning and arranging the various levels of the tower at night while the dragon is home, and your work has to pass an inspection. Then during the day you are locked in your room, and have some ability to watch a prospective rescuer attempt the dungeon crawl without your direct input. But you can strategically place items, enemy spawns, and Dark Souls style hints to try to tip the scales. So kind of like a tower defense in reverse where you are trying to lose.