Good question, I never had a voodoo card to compare against my Guillemot Cougar Riva TNT2 and probably was better but stick with Direct X as you are wanting to play other old games.
My other old cards for Win98 were NVIDIA Geforce2 MX 64mb, Geforce4 Ti 4600.
How did you get on testing each troubleshooting selection and applying the patch to your ATi, as maybe last hope. Such as ticking force 3d and then pressing ok and applying the patch to your card. Then unpatch and tick another selection like single scene etc. Also try ticking both the no 3dfx and mmx options.
Could you try different refresh rates set on the ATi control panel and win98 display settings, although might be fixed at 60 Hertz but try 50 or 75 and maybe 100 if possible.
I reckon it will require hooking up the laptop to an old CRT monitor that is capable of 100mhz refresh rate but no guarantee. Will continue thinking of other potential solutions.
Very well done and can remember your wizard only entire campaign from years ago. I shall enjoy watching this one all the way through. Thanks
(Try dgvoodoo2 control panel to make the game look even better if you aren't already, as I noticed the dgvoodoo2 watermark which is on by default but can switched off via the control panel, see the help fix guide)
Rick Priestley interviews by Filmdeg Miniatures, regarding history of creating the Warhammer rule books. Good to hear his favourite was 4th Edition like Dark Omen.
1.) Check you're using the correct version of dgvoodooo 2.6.3 as the newer versions don't apply their settings.
2.) Also check antivirus isn't blocking dgvood2 control panel
3.) Check that dgvood2 control panel is using the correct path, as should be applying setting to C:\Program Files (x86)\Dark Omen\PR_Eng and not C:\Users\...\AppData.
4.) Tick and untick the watermark setting to test that the settings are being applied and then try different screen resolutions.
Yeah ATi was always worse than NVIDIA, I had the same with Operation Flashpoint on a 256mb Radeon and had to swap to NVIDIA Geforce and never used them again. You should be able to find a cheap Win98 setup with NVIDIA card.