So for wide-screen any 3:2 aspect ratio will work, use your monitor native vertical dimension, like 1050, and multiply 1.5, horizontal dimension is 1575, I tried 1575x1050 and work perfectly.
flim's method is actually a workaround to minimize damage in all Vert- games, but in my experience Dark Sector is still Vert-/stretched in fullscreen 3:2, so this is hardly a solution. :?
Anyway, big thanks to Voodooman and everyone who contributed to shed some light upon this mess !
Here are updates for various sections of the DR, hope StingingVelvet and The_cranky_hermit can put these to good use.
==Method==
.ini
Native support results in a vertically stretched picture in fullscreen. To get a properly scaled game, you need to enable windowed mode, as explained by Voodooman:
1) Enabe hidden windowed mode
C:Program FilesND GamesDark SectorConfigs
DS.cfg
[Windows_Config,/Types/Config]
Add this line:
Graphics.FullScreen=0
2) Set resolution
C:Program FilesND GamesDark SectorConfigs
Editor.cfg
[MainGameWindowed,/Editor/WinRect]
SizeX=
SizeY=
==Screen change==
Vert-
4:3, fullscreen
16:10, windowed
16:9, windowed
==Supported resolutions==
The game fails to run at any resolution wider than 2048 pixels (all you get is a black screen with piled up menu items even during gameplay).
==Aspect ratio support==
16:10, 15:9, 16:9, tallscreen and faux TripleHead are all supported in windowed mode. The horizontal FOV is fixed, the vertical FOV changes with the AR.
==Multiplayer Support==
Not tested. Method relying on user config shouldn't be a problem...?
==HUD Stretch==
None. The HUD does not scale at all, so 2D elements look the same but are closer to the top and bottom of the screen in 16:9 than in lower ARs.
==Cut-scenes==
Rendered in-engine in real-time and Vert-.
4:3, fullscreen
16:10, windowed
16:9, windowed
==Surround Gaming support==
None for the reasons mentioned above: Vert- gameplay and limited max width.
1920x400, windowed