Torn between fear and curiosity, the player will have to make choices – will you open the sealed coffin? Will you give the stranger a ride to the next island? Will you dare eat the sea monster's meat? The likelihood of success for some actions depends on the strengths of your attributes; many others will be available if you're willing to pay a price: gold, fuel, food, crew members, treasures, Fragments of Secrets (i.e. experience points), or even attribute points.

If you manage to return to London alive, you can collect the bounties for your accomplishments and hope that the sacrifices made allow you to come out ahead. On your next trip, you may be able to undertake actions that were previously locked to you. If, however, you perish among eldritch horrors and cannibals, the game will have to be played from the very beginning and the Unterzee's islands will be randomly redistributed. But you may play as your heir, cashing in on heirlooms you have left to yourself.

Sunless Sea is inarguably an RPG, but one that isn't tied to conventions. Most RPGs are structured around progression and exploration; Sunless Sea subverts both. Despite an ultimate goal to achieve, there isn't a linear sequence of main quests that leads you to it. Instead, you have countless small "storylets" that are only vaguely interdependent. Also, progression isn't fixed, and whatever rewards you gain can easily be lost. Exploration, a major part of the game, is never free, neither of care nor cost. Sunless Sea imbues the journey into the unknown with danger and mystery.

Sunless Sea is one of the few games that lives in the mind as much as on the screen; its secrets aren't just there to be ticked off, but to be savoured. Sometimes, imagining what lies in the Zee is the best way to enjoy the game. How fitting for a game about the dark and the ocean.