niisaka at Tari Lari Run has developed a method for playing Mountain of Faith, Subterranean Animism, and Undefined Fantastic Object on vertically-oriented monitors.
Download the zip file at this site and extract it into the game of your choice.
When you start the game, it will automatically hook to this .dll. From there, there are many options for adjusting the screen. By holding Alt + an arrow key, you can change the orientation of the picture. Note that the menus won't look any different, but one you begin the actual game, it should look something like this:
Note: In order to use this method, do not use your graphics card's orientation settings. This pretty much means you'll have to turn your monitor when you want to play the game, and turn it back when you're done.
There are other options in the th_pivot_custom.exe.
The first set of options is the filter. From top to bottom, it's Bilinear, B Spline, Bicubic(simple), Bicubic(corrected), and Lanczos2. Next to those options is the sharpness level. The checkbox is whether or not you can change the filter from within the game, using Alt + PageUp and PageDown.
The second set of options is the orientation - 0, 90, 180, and 270 degrees. I believe most monitors need 270 degrees for this. Again, the checkbox turns on in-game rotation, so use Alt + arrow keys to change it if needed.
The bottom left button is to uninstall(by erasing it from the registry).