Mind Candy sold 256 puzzle cards to fund a £100K treasure hunt across two worlds

Perplex City, launched by London gaming company Mind Candy in 2005, was an alternate reality game in which 50,000 players hunted the ‘Receda Cube’ through puzzle cards sold in shops, websites, live events, voicemails and text messages. In February 2007 web designer Andy Darley dug the Cube out of Wakerley Great Wood in Northamptonshire and claimed the £100,000 prize. The 256 puzzle cards - sold in packs, ranked red (easiest) to silver (hardest) - were how Mind Candy monetized the game: standalone brainteasers carrying lore, feeding points into player leaderboards.

Card #256, 'Billion to One', was the last unsolved silver card: a photo of a smiling man of Asian appearance in front of European timbered houses, captioned 'Find Me', with one hint - 'My name is Satoshi'. Players located the backdrop (Kaysersberg, Alsace) but never the man. Laura E Hall kept the hunt alive for years, winning Guardian and New York Times coverage; she even got within one step of him via a tip. Years later she learned her partner - Mind Candy designer Jey Biddulph - had designed the card and known the answer all along.

In 2020 a YouTube channel’s video restarted the search on Reddit and Discord. Tom-Lucas Säger ran the photo through PimEyes, a consumer reverse-image search, which surfaced a 2018 party photo - unindexable before that year - leading to Satoshi Shimojima, then 49, a Japanese car-parts executive, who emailed: ‘I am Satoshi, who you have been looking for!!!’ The card had become a 14-year measurement of what the internet could find - and of how face search turned a party game into a privacy question.

Sell packs of 256 ranked puzzle cards in ordinary shops: each card is a standalone brainteaser that also deepens the fiction - the collectibles ARE the business model.

Selling card packs gave an ephemeral web game physical shelf presence and unit economics - players paid per puzzle whether or not they ever joined the meta-hunt.

Each card worked both standalone and as lore, so one product served casual puzzlers, completists and the 50,000-player hunt at the same time.

The Billion to One card was built to be solvable only through collaborative detective work - a puzzle tuned to the network hubs of its day, which is why it resisted the internet for 14 years.

A game with no shelf presence invented one: make the collectible itself the product, with each piece working standalone so buyers who never join the meta-hunt still pay for the world.

The Cube was found in 2007 (£100,000 to Andy Darley, who donated to the Unfiction forum that archived in 2018); the final card fell in 2020 after PimEyes indexed a 2018 photo. The Satoshi prize fund was split between Hall and Säger and given to charities. Designer Biddulph doubts anyone would agree to be 'found' on a card today - the same mechanism now reads as a surveillance caution.