Had a chance to properly sit down and try running the game with the command line arguments. Had a mixed bag of results. I've uploaded some images to Imgur
https://imgur.com/a/acdDl If I set the output device in Setup to use OpenGL, and supply the arguments listed above (and using the 32bit patched main.exe) I get:
1) A tiny gameport window with the text shown at the top of the screen (image 1 & 4)
2) The menu uses the normal 4:3 ratio (a good thing) (Image 2)
3) Its a bit darker than using 3dfx
4) The mission intro fly-by runs at a widescreen ratio using the full 1920x1080 (Image 3)
If I swith the output to use 3DFX, and set nglide to use the Vulkan backend:
1) The arguments are ignored and game runs at default resolution
If I use 3DFX output, with nglide set to Auto backend I get:
1) The game menu is squashed into a widescreen res and the text looks awful
2) The game now fills the 1920x1080 space however the bottom of the UI is chopped off (and the text looking iffy) (Image 5)
So is there anyway to get the OpenGL version to actually fill the viewport rather than be a tiny window?