I absolutely love the unconventional and incredibly deeply layered puzzle RPG Blue Prince. Enough people before me have pointed out that the mechanics of Blue Prince lend themselves to the horror genre. I'm not here to repeat that. Instead, I had a specific DLC or spin-off idea today that I wanted to share. The information you are about to gain are part of the game's exposition and an integral part of the game's core mechanic. I thus don't consider them a significant spoiler.

In the entrance hall letter, the protagonist's grand-uncle Herbert S. Sinclair explicitly states:

YOU MAY NOT STAY OVERNIGHT.

This enforces the core rogue-like deck builder looping mechanic of the game. Once you used up your steps for the day, you have to start a new run without any items and with an empty house. I should also note that you never meet any of the mansion's staff, even though you can find all sorts of items and trinkets belonging to them, can find evidence of them communicating, and continuing their work (for example through the 'dinner is served' mechanic).

The labyrinthine ever shifting nature of the mansion paired with its elusive staff reminded me of the endless IKEA SCP. What if there was an item that did allow you to stay the night, unlocking a new gameplay layer?

In the game's logic, progressing across the ranks of the mansion corresponds to the progression of the clock (again, see the 'dinner is served' mechanic). To make this mechanic sufficiently obscure and somewhat challenging to unlock, I was thinking of the following:

• New Activated Item: The sleeping bag. Only spawns after you have reached rank 9. The sleeping bag can be activated only while you are inside a bedroom. When activated, the sleeping bag "refunds" you any number of steps spent since you last entered a bedroom minus 1.
• There may also be some interaction with other rooms, e.g., if you paid The Great Alzara today, maybe you get a dream with another vision.
• On its own, the sleeping bag would be a rare but powerful item. If you play it right, it can give you a significant late game step boost to keep strong runs going. However, here's the twist: When you regain more than 9 steps using the sleeping bag, for every additional step regained this way, there's a certain chance you have a nightmare; e.g., a 10% chance for every step regained beyond 9.
• The Nigthmare would be a whole new layer of the game: All rooms of your current map become twisted, grotesque, and morbid. There's a certain chance that doors are now closed that had been open before and new passage ways may appear. You can't open your map. You can't end the current run except by finding your way out of the mansion with your remaining steps or by being cornered by the servants:
• ...faceless creatures whispering to you "You really should not be here at night, Master Simon!", "Your Grand-Uncle would not approve!", "Haven't you been told that you must NEVER spend the night at Mount Holly Estate?", hunting you through the maze to corner you, leading to a creepy game-over screen and looping back to a new normal run from the Entrance.
• Other regular mechanics do apply, e.g., you can open doors and draft rooms, but drafting happens with a darkroom-like penalty, i.e., blinded selection.
• Copious interactions with existing items, e.g., the Torch to make light, the salt shaker to block of entrances for pursuing servants, the Repellent to push back pursuing servants for a brief while, etc.
• Copious interactions with existing mechanics, e.g., the Security Room to see the servants stalking you, look them in / out of areas, avoid their paths.
• Hide and seek mechanics similar to Amnesia: The Dark Descent.

Anyway, these were my five cents. Don't think I had the skills or time to make it into reality. But if someone at Dogubomb or elsewhere feels inspired: Please let me know.

I like the way you think!