butcer: When i put resultion to opengl default the game crashes
alright i read that renaming the exe to quake2.exe would fix it and it did, i have no idea why and i find that very odd but hey it worked
This is a known issue with nVidia drivers.
Basically, GOG set the game up to run with nGlide for 3DFX emulation. If you go with OpenGL (default) then it uses your graphics drivers solely without any 3DFX emulation, so you lose the 3DFX features. I personally don't think it is a good choice to play this game using OpenGL (default) as nGlide is superior for me and that is enabled by using OpenGL (3dfx), but I understand that different people have different opinions and also different machines may have different performance through the nGlide 3DFX emulation.
So, as you found, renaming the executable to quake2.exe fixes it, and this is because SiN uses the same engine as Quake 2 but whilst Quake 2 has a set profile within the graphics drivers, SiN does not. This means that when running quake2.exe the graphics drivers use a profile that fixes the problem, but running sin.exe doesn't trigger that fix.
You can just rename the executable as you have done, but if you wish to create a fixed profile for the game then you need to use nVidia Inspector. Using this free tool you can navigate the profiles in the nVidia drivers and see that for Quake 2 there is a setting turned on for Extension Limit. If you create a profile for Sin and turn on this same setting then this will fix the game without you having to rename the executable. Bear in mind that any re-installation of the drivers will remove any custom profiles you've created so you may wish to export any profiles you create for later use.
You can find more info in the below threads:
http://www.gog.com/forum/sin_gold/if_youre_having_trouble_running_sin_try http://www.gog.com/forum/sin_gold/i_dont_like_nglide_here_is_what_i_found