Baseline (Widescreen) Solution & Issues
Open forces.exe with a hex editor and replace AB AA AA 3F with your chosen aspect ratio (see Common HEX Values).
Everything 3D is Vert-. The menus and HUD are stretched from 4:3.
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
FOV is too low. HUD is messed up.
Eyefinity / Surround Specific Solution & Issues
FOV is far too low. HUD is messed up.
4k UHD Specific Solution & Issues