So, I had a great deal of trouble getting this game to run on Windows 10 and a 21:9 monitor. The in-game settings also leave a lot to be desired and don't seem to include important functions like a windowed mode or aspect ratio. I found a way to make the game run a lot better for me by digging around in the .ini files and forcing it to run in the original aspect ratio.

The file we are looking for is in the game's local files. Here is the path through file explorer:
(your steam library folder)>steamapps>common>Sherlock Holmes versus Jack the Ripper>game.ini

I would make a copy of the game.ini file just to be safe. Open the file in notepad and scroll down through the various settings. Under [render] change fixed_aspect_ratio to true. After the change it should look like:


Save your changes and launch the game again with this edited settings file. The game should now display in 4:3.

Making this change will still display the game in fullscreen, and there will be massive pillar boxes on either side of the 4:3 image. This made the game a lot easier to control for me, though. With the default settings, the game was enlarged so the sides of the image reached the left and right edges of my monitor. This was the case whatever resolution I used. Large slices of the top and bottom of the image were cut off and I couldn't click on some of the clues because they weren't "in the shot." The interface of the journal and the puzzle sections were also really stretched. Forcing it to 4:3 gave me full view of the game and made the GUI and the mouse cursor look normal again. I think this was how the game was originally displayed, and it's much easier on the eyes. The first-person mode was also a lot prettier and didn't make me sick with the switch to 4:3.

I hope this helps you out!