The game calls ChoosePixelFormat with cColorBits set to 32 and all the other counts being 0. Then even if the format is missing depth it still uses depth testing and renders with glitches if that doesn't work. On an Nvidia machine here it happens to end up with 24 / 8 depth stencil anyway and works. On AMD machine it ends up with 0 / 0 and has the problem. On the same machine with Win11 and the same ChoosePixelFormat PFD it ends up with 32 / 8. Frankly I am not sure that with every possible GPU and driver it will get a non-zero format (and the game warns about buggy drivers when selecting OpenGL option which suggests that it doesn't necessarily work very well on arbitrary instance). But I suppose there is nothing wrong in matching current Windows / AMD behaviour here instead of depending on unspecified format order.