Baseline (Widescreen) Solution & Issues
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
What you need to do: Change the Aspect Ratio from 16:9 to 21:9
Go to --> ...\Steam\steamapps\common\Flame Over\FlameOver_Data\Managed
Hex Edit the Assembly-CSharp-firstpass -> look for 39 8E E3 3F and change the to CD 90 18 40. Fix available from the PC Gaming Wiki Community Files (search there).
Since the Game is optimized for 16:9 you will see some Graphic Flaws like the HUD stays in 16:9.
Eyefinity / Surround Specific Solution & Issues
4k UHD Specific Solution & Issues