Players navigate the game world via an upgradeable interstellar locomotive, and can interact with various narratives both brief and long that may have positive or negative rewards.

[1] The game is set ten years after the events of Sunless Sea, after the subterranean city of London opened a gateway known as the Avid Horizon and gained access to outer space, here called the High Wilderness, where stars are godlike beings who exert power through their light and unspeakable terrors lurk in the dark.

The player assumes the role of a crewmember on a ramshackle locomotive who inherits captaincy of the vessel and a strange black box after the previous captain is mortally wounded.

The player is free to pursue the mystery of the box, embark on a career as a trader and retire wealthy, fight in a war between the Empire and rebellious colonists, or seek out answers to a dangerous question: why are the stars dying?

[1] The development team cited the science fiction and planetary romance works of authors C. S. Lewis, H. G. Wells, and Leigh Brackett as influences along with Art Nouveau and the 1999 game Planescape: Torment.

[12] On 28 April 2021, Failbetter set a tentative release date for the Sovereign Edition for 19 May, cautioning that this could still be delayed if the certification processes for console versions encountered unexpected issues.

[14] Upon the game's release in January 2019, Sunless Skies was praised by critics, receiving a Metacritic score of 87, indicating 'generally favourable' reviews.