Hi, I've seen this guide multiple times just to upscale to 4K, but wanted to update it just so you know now that the mod supports ultrawide resolutions and also windowed and borderless window mode, so here's the guide.

1- Download the mod from here: https://github.com/Lyall/MGSHDFix

2- Extract MGSHDFix.ini MGSHDFix.asi and d3d11.dll on the game's root folder.

3- Open MGSHDFix.ini, there you'll see width and height, leave it at 0 if you wanna use you desktop's resolution.

4- If you want to play in Windowed or Borderless, under the resolution change "false" to "true" in the mode you wanna choose.

5- You're good to go, enjoy your game! <3