Sunless Sea made a transition from Unity Engine 4 to Unity Engine 5 - and with it a long awaited feature could finally been realized:
now you can adjust the size of the text on screen with the new options-menu!

What may sound like an irrelevant feature, finally solves a real problem for people like me with high screen resolutions.

Many, many thanks, dear developers!

UI and Text Resizing

Sunless Sea was made in Unity 4, which had some limitations particularly around the way it handled text. As a pretty text-heavy game, we ended up with many players finding the game unplayable due to their screen resolution. Text was tiny or fuzzy. Not ideal!

Happily, in Unity 5 we’ve been able to do a lot more with the user interface, and have fixed the fuzzy/tiny text problems (with the help of everyone who opted into the Unity 5 beta - thanks!). Please enjoy fiddling with the size of your text and the gazetteer to your heart’s content.

Source: Steam