On 3 September 2013, Failbetter Games launched a Kickstarter campaign to crowdfund "Sunless Sea" with a funding goal of £60,000. The project was successfully funded, receiving around £100,000 from over 4000 backers. On 13 May 2014, the studio launched a Greenlight campaign to release the game on Steam. The game was approved 15 days later. On 17 June, the game was soft launched on the developer's website, a Steam early access build was later released on 1 July. The game officially launched on 6 February 2015.