Sunless SeaSunless Sea has already been available via Early Access on Steam, but it reaches version 1.0 on February 6.
I've been playing it for a few weeks, and it is a deeply atmospheric, unusual experience. Here's the description from the Steam page:
Take the helm of your steamship and set sail for the unknown! Sunless Sea is a game of discovery, loneliness and frequent death, set in the award-winning Victorian Gothic universe of Fallen London.
What strikes me most is how carefully this game has been crafted. It is beautifully constructed, and if it were a physical good, it would be handmade.
I don't want to give you any spoilers, because the game is quite unique, but it is absolutely worth large amounts of your time.