The Moonstone

A priceless diamond is stolen from a country estate. The next morning, a housemaid is found dead. Five members of the household each know something, but none of them know everything.

Play The Moonstone  — free, browser only, takes 30–60 minutes.

You play Sergeant Cuff, a detective dispatched to investigate both the theft and the death. Your only tool is correspondence. You write freeform messages to each suspect and they write back in character. No dialogue trees, no scripted paths. You decide what to ask, who to press, and when to call someone's bluff.

Not everyone wants to help you. Some characters are guarded, some are protecting someone else, and you need to figure out how to win them over before they'll give you anything useful. Cross-reference what different characters tell you, spot the contradictions, and make your accusation when you think you've worked it out.

How it works

Each character has a unique personality, knowledge, and agenda. The mystery has a specific solution — you piece it together by cross-referencing what different characters tell you and spotting where their stories don't line up. Characters remember your earlier correspondence and react to your approach. Press too hard and they shut down. Ask the right question and they might let something slip.

Based on Wilkie Collins' The Moonstone (1868), widely considered the first detective novel in English. The original novel is told entirely through letters and testimony, which is what made it work as a game.

The Cast

	Gabriel Betteredge Butler. Forty years of service. Knows every secret the house has ever kept, but buries them under anecdotes and Robinson Crusoe quotes.
	Rachel Verinder The birthday girl. Proud, furious, and refusing to talk. Getting anything out of her takes patience and the right question at the right time.
	Franklin Blake Rachel's cousin. Charming, well-travelled, and eager to help. The trouble is, he can't remember several hours of the evening in question.
	Dr Candy The local physician. Helpful on the surface, but something is eating at him. Changes the subject whenever the conversation turns to the night of the dinner.
	Jem Yolland The fisherman who found the body. Plain-spoken, practical. He knows what a drowning looks like. What he pulled from the Shivering Sands that morning didn't look like a drowning.
	Superintendent Seegrave Your superior. Expects results by Friday. Write to him when you're ready to make your accusation.

Created by George Thomas.