So i can set the resolution to 1920x1080 just fine... but the game is still stretched. I already tried the console command "fov 110" and i also set a parameter in the config.cfg in my gameprofile, but nothing changes. Does anyone have an idea to get the changes to work?

There's a working solution here: http://www.wsgf.org/dr/sin/en

It's vert- but still better than stretched imho. Should work with both the GOG version and the Steam version.

Just tried the fix out again, and it actually seems to be Hor+ if you use the fov command after applying the patch.

Even the screenshots on the fix page show it's Hor+, so I'm guessing the Vert- mentioned on the fix page might be a typo.

Last time I tried widescreen with sin, I could get the proper fov to work in the game itself. But all the interactive computer consoles were cut off at the tops and bottoms, they seemed to use some separate fov value I could never find.

That was why I went back to 4:3 aspect ratio. Granted this was with the steam version. Have yet to try any widescreen with the gog version.