Failbetter Games has announced a crowdfunding campaign for Fallen London. The campaign isn't for a videogame spin-off but an official Fallen London TTRPG being developed alongside Magpie Games.
The Fallen London TTRPG Announcement
The Fallen London TTRPG was announced on Bluesky Social by the official Failbetter Games account. It announced that the Kickstarter campaign will go live on February 11th at 10 AM ET.

In addition, if you sign up for their official newsletter, you will receive a Quickstart Guide for the game. This guide contains six premade characters, the core rules, and a playable adventure titled "The Disappearance of the Transfigured Poet."
The official Kickstarter campaign page promotes additional incentives for the Fallen London TTRPG. In addition to several physical products, the core rulebook, a GM screen, custom six-sided dice, etc., stretch goals include digital items for your character in the Fallen London browser game. Lastly, those who back the campaign in the first 48 hours will get a physical Devilbone Die at no additional charge.

The campaign doesn't state what system the Fallen London TTRPG will run on. However, given Magpie's track record of adapting properties like Avatar: The Last Airbender and Root, there's a good chance it will use the Powered by The Apocalypse system. A mechanically light, story and character-centric system where players just roll 2d6 to resolve challenges.
Fallen London made its debut in 2009, originally under the name Echo Bazaar, as a browser-based interactive narrative game. The game was packed with branching story decisions, involved Ambition Quests, and in-depth worldbuilding of a version of Victorian London that had sunken into a vast cavern under the Earth called the Neath.
In this new suberranean home, London changed into something twisted. The city streets twisted into a labyrinth, inhuman creatures arrived trading in esoteric goods like human souls. and even physical law itself has faded in this state of darkness. The original experience is still receiving new quests and updates to this day.
Alongside the impressive longevity of this main game, Failbetter Games has developed other titles set in the Fallen London universe. These include the shipfaring horror game Sunless Sea, the sequel Sunless Skies, and the visual novel Mark of the Rose.