So having done some research and testing, I've found that Half-Life's infamous gl_overbright feature only seems to work in OpenGL/Glide MiniGL mode if it detects that the graphics card has only 1 TMU. The only alternative to this is using Direct3D mode, but that has other graphical artifacting.

I'm lucky enough to have a 3DFX Velocity 100, where I can switch between 1 and 2 active TMUs for OpenGL/Glide via a registry hack, so I can get gl_overbright working, but at the cost of lesser performance and switching back and forth the registry value.

For reference, I'm using WON version 1.0.1.6 because it's before the changes and broken stuff in the 1.1.x.x patches. This issue also exists in the release build (1.0.0.9) as well.

With all this said, is there any sort of hack to get gl_overbright working in GL modes with both TMUs active on Win98? I'd prefer not to swap back and forth all the time, even if it's just from a reg backup file.