Baseline (Widescreen) Solution & Issues
Native Anamorphic till 1600×900 for higher resolution go to --> ...\steamapps\common\sacred_citadel\sacredcitadel.ini
and change ScreenWidth=2560 ScreenHeight=1440.
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
The Game is VERT- for 21:9 - you need to HEX & ini edit to get it HOR+
INI edit resolution: Go to --> ...\steamapps\common\sacred_citadel\sacredcitadel.ini
and change ScreenWidth=3440 ScreenHeight=1440.
Hex edit FOV: Go to --> ...\steamapps\common\sacred_citadel\sacredcitadel.exe
Look for C7 71 FC 3F and change it to C7 71 08 40 in Offset 17E720
Fix available from the PC Gaming Wiki Community Files (search there).
Eyefinity / Surround Specific Solution & Issues
The Hex edit Solution does not work for Surround. The Game is zoomed in too much..
4k UHD Specific Solution & Issues
INI edit resolution: Go to --> ...\steamapps\common\sacred_citadel\sacredcitadel.ini
and change ScreenWidth=3840 ScreenHeight=2160.