A social deduction game for iOS

Gaslight on the Thames

Moriarty has infiltrated Scotland Yard with corrupted intelligence. Host an investigation, let every sleuth join from their own device without Wi-Fi, and expose the contradictions before the fog swallows the truth.

Download on the App Store Learn the Game

London, 1887

Fogbound streets. Flickering truths.

Three envelopes wash ashore on the banks of the Thames: a Location, Evidence, and a Suspect. Every genuine detective receives the same trio of truths. Only Moriarty's dossier is tainted with two decoy words—and he doesn't know which of his three words matches the detectives' intel. Under the gaslight, the difference between earnest testimony and elaborate bluff is razor-thin.

Gaslight on the Thames is a tabletop-inspired social deduction game for iOS. Connect nearby devices instantly with Multipeer networking, trade cryptic hints, expose contradictions, and vote to unmask the traitor before he vanishes into the fog.

Why it stands apart

Designed for tension. Tuned for storytelling.

Nearby-device camaraderie

Host from one iOS device, invite detectives in the room to join for free via Multipeer, and debate face-to-face while the app tracks every clue.

Shared truth. Corrupted intel.

Detectives share the same three genuine words. Moriarty’s trio hides two personal decoys, and he doesn't know which word is real. Your job is to hear the tells.

Dynamic difficulty

Scale the tension with Auto, Easy, Medium, or Hard word pools, adjustable timers, and optional twists like Irene Adler.

Cinematic Victorian atmosphere

Original art, brass-soaked soundscapes, and fog-laced UI immerse you in the mystery of late 19th century London.

Four iconic roles

Who will you become beneath the gaslight?

Illustration of Sherlock Holmes

Sherlock Holmes

Knows all three genuine words and both of Moriarty's decoys. Guide the Yard without revealing your omniscience.

Illustration of Dr. Watson

Dr. Watson

Knows which genuine word Moriarty received. Signal allies subtly and stay off the villain's radar.

Illustration of Irene Adler

Irene Adler

A wildcard presence. She wins by being eliminated, forcing everyone else to lose. Suspicion is her sharpest blade.

Illustration of Moriarty

Moriarty

Receive three words, only one of which is genuine—but you won't know which. Bluff convincingly, mask your uncertainty, and steal victory by outing Holmes or Watson during the reveal.

How it works

Three steps to trap a mastermind

  1. Receive your intelligence

    The host distributes three secret words to every player. Detectives get the same trio. Moriarty receives one matching word plus two unique decoys—but must deduce which is genuine. Memorize them; no screenshots, no second chances.

  2. Share cryptic clues

    Describe your words without naming them outright across two clue rounds. Cross-examine contradictions, challenge hesitation, and pay special attention to anyone dodging a shared detail or sounding unsure of shared intel.

  3. Vote and reveal

    When the gaslight burns low, accuse a suspect. Catch Moriarty and keep Holmes and Watson hidden to win the night—or watch the villain claim victory during the reveal. Ties fall to Irene if she's in play, and against Moriarty if she isn't.

Set the stage in the lobby: the host (unlock required) configures special roles, timers, match length, and difficulty before nearby detectives join automatically via Multipeer networking.

Player Count

3-8 detectives on nearby devices

Session Length

5-15 minutes per investigation

Play Style

Nearby-device social deduction, party-ready

Download & availability

Bring the investigation to your table

Download on the App Store

Universal app for iPhone and iPad. Requires iOS 16 or later.

  • Host unlock: One-time in-app purchase enables hosting; joining is free.
  • Connection: Nearby-device Multipeer networking—no shared Wi-Fi needed.
  • Session length: 5-15 minute investigations keep the table talking.