Baseline (Widescreen) Solution & Issues
Uses Hor+ scaling. FOV slider is also available which rangers between 64°-99° at 4:3 aspect ratio and is recalculated correctly for each aspect ratio (73°-110° at 16:10, 79°-115° at 16:9 aspect ratio, etc.).
However, as of version 1.21, the aspect ratio seems to be stored in the save files, which may cause issues in rare cases, in which the user's aspect ratio changed between save files. To fix the aspect ratio, the user must load the save file, then go to options while in-game (instead of the main menu!) and then set a resolution to the new aspect ratio, preferably finishing the process, by clicking "Save and exit" to create a new save file with the newly set aspect ratio.
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
Some cutscenes are pillar-boxed to 16:9.
32:9 aspect ratios too wide and result in menus displaying minor graphical glitches.
Eyefinity / Surround Specific Solution & Issues
Menu and loading display graphical glitches at "emulated" 3840x720 (3x 16:9) - tests on proper Eyefinity / Surround setup should be done to confirm it.
4k UHD Specific Solution & Issues