When I select a resolution option higher than the default one (or any other visual option) and apply the settings, the screen goes black for a second, there are the usual option loading sounds, and then nothing changed.

I'm using win7 64 bit

Using 3dfx renderer? Use the nglide configurator located in the game folder.

I've changed nGlide resolution to 1920x1080, but ingame resolution is stuck at 640x480. Anybody know how to fix this?

Dont care what in-game is telling, if you enabled 3DFx true resolution is the one from nglide config. Menu and loading screens have max 640x480 but are upscalled in nglide to fullscreen, if you set bigger value in default opengl they will be too small and have black space around it. Normal in-game levels, textures and models are properly scalled to your chosen 1920x1080 along with the menu and loading screens.

Are you saying I cannot use sinpatcher (http://www.wsgf.org/dr/sin/en) with GOG version? Steam version works fine in 1080p using sinpatcher. Since I cannot change resolution in GOG version UI looks upscaled/stretched if just by using nGlide config.

Can we get a screenshot so that we can see what you are seeing?

Steam: http://imageshack.com/a/img23/8467/0i1y.png
GOG: http://imageshack.com/a/img809/3365/si41.png

To use resolution from sinpatcher you need to change your rendering mode to Default OpenGL and then to you overwritten resolution by patch. As for if game is blurred or not in 3Dfx mode, compare:

640x480 (Default OpenGL) - blurred and darker overall
http://i.imgur.com/X0qLwm0.jpg

640x480 (3Dfx OpenGL) - sharper and lighter, more details, nglide
http://i.imgur.com/poypn1P.jpg

1280x720 (3Dfx OpenGL) - sharper and lighter, more details than previous 640x480 definitely not blurred textures, nglide
http://i.imgur.com/GdzKJXl.jpg

Doh! I'm an idiot. I knew I forgot something. Steam version is probably using OpenGL. I couldn't find an option to switch between OpenGL and 3Dfx. I know GOG version has that option.

Btw what do you mean when you say "more detail"?

See first two screens above.

Default OpenGL has simplified rendering without some shiny, dynamic, advanced lighting effects and displaying textures, variety of height, geometry, as you can see on very basic comparison in the same resolution (640x480). 3Dfx don't have that fog and darkness effect and can render more details at once visible on screen. staying clear and sharp

Thanks for the explanation. I couldn't tell from screenshots.

Last question: is there any way to change ingame "Video Mode" using "Video Driver" set to "3Dfx OpenGL" to anything other than 640x480?

That only will change size of HUD, cursor and menu/loading screens but the resolution of in-game screen is still controlled by the 3Dfx driver and it's external resolution settings, the same applies for gamma, trying to change it in-game while in 3Dfx mode won't work.

I attached image what happen if you change resolution to (for example) 1024x768 Default Opengl.

Also if I remember, sinpatcher has problems with FOV of computer screens when you try access and hack stuff.

Problem solved! For me at least. It wouldn't let me change "Video Mode" to anything other than 640x480, but it works now and UI scales fine.

Thanks HenitoKisou for the help!

Just brought it, and its working with nGlide as some options (such as aspect ratio work) however resolution doesn't change at all from 640x480 (even when it should be 1920x1080 as set in nGlide., and this is in game not on menus.)

Edit: I Dont use Sin Patcher and I have 3Dfx set in the game options.

I had to install nglide v2.00 sett my settings (1080p).
And then start the nglide in installation folder. v0,99 and just change resolution then save.
Then it did work.