Mori_Yuki: Thank you for telling me! Does this mean that this option is exclusively used in window mode? If so is there a way to maybe change the resolution when playing in full-screen mode? I'm not convinced that it would make much of a difference, bu-uuuuu-ut doesn't hurt to ask. ;-)
MarkoH01: I can only guess - but yes, it seems to be a scaling option for windows mode only since the scaling factor in fullscreen will be automatically chosen based on your resolution (so how much does the original resolution be scaled to provide fullscreen).
I've played this game now for 5 hours in 1080p and fullscreen and never had the impression that it was ugly ... maybe this is a subjective thing. I also never had problems with Darkside Detective (similar resolution) or The Last Door (even lower resoution) - but I also do understand that some simply might dislike such graphics. For me these are working good for this type of game.
Meantime I had the chance to try and it actually only works for window mode.
The graphics start looking ugly once the camera zooms in on a scene. One of the cut-scenes very early on just look plain bad because the picture is pixelated and without much detail to speak of. Developers should have used a fixed distance camera and I can see why they didn't. Bigger camera space means higher resolution equaling more work for the guy doing creating the graphics. They obviously decided to work with zoom-factors and filters in Unity and the outcome isn't very good. Here is an example where the background starts to lose detail
https://ibb.co/sP5YPp5 and the picture looks blurred. Also when running around background graphics on signs and other small details start shifting which I guess wouldn't otherwise be noticeable if it was at displayed at greater distance than is the case. If developers had decided to zoom out and keep the Unity camera at a fixed distance and angle this game would look perfect.
I usually like pixel style games when done right. When deciding to use this art style do it right and do it justice. Which to me this game or Inspector Waffles just doesn't and both for the same reasons: Overblown pixels and zooming in so close that I feel thrown back to the early 90's playing Snoopy. So, yes, this opinion and what I have already said apropos the graphics of Lacuna Prologue is highly subjective. ;-)