I did it!
I upgraded to Win10.
And it happened as it has to be... UT2004 crashed on every start with a critical error.
To activate the OpenGL driver and to deactivate the ReduceMouseLag option in the UT2004.ini didn't work in my UT2004 installation i had used for years.
This is how it worked for me:
1. A clean new installation of UT2004 (of course one first has to uninstall the old one).
2. Open the UT2004.ini and change the settings as following:
3. activate the OpenGL driver: (the semicolon deactivates what follows right on it in the same line)
[Engine.Engine]
;RenderDevice=D3DDrv.D3DRenderDevice
;RenderDevice=D3D9Drv.D3D9RenderDevice
;RenderDevice=Engine.NullRenderDevice
RenderDevice=OpenGLDrv.OpenGLRenderDevice
;RenderDevice=PixoDrv.PixoRenderDevice
Don't change the Render Engine setting ingame. Your UT will crash afterwards again.
4. turn off the ReduceMouseLag option:
[D3DDrv.D3DRenderDevice]
ReduceMouseLag=False
[OpenGLDrv.OpenGLRenderDevice]
ReduceMouseLag=False
... etc.
(etc. means you have to search for the option and turn it off in every single case)
Now UT runs at least. But I made several other changes in the UT2004.ini.
For example setting up the resolution (it doesn't work ingame with my WQHD resolution)
5. change resolution:
[WinDrv.WindowsClient]
FullscreenViewportX=2560
FullscreenViewportY=1440
All the other changes i made were just a matter of my own habits. I will post them
in another thread.