Topic on User talk:Eddmanx
It's important to not that DirectX and Direct3D aren't the same thing. DirectX is simply a suite that contains APIs, among them is Direct3D.
A game that requires DX8 to be installed doesn't explicitly mean it also uses D3D8. For example there are OpenGL games which do not use D3D at all and yet need DX because they need its, say, audio or controller APIs.
For tracing download and apply the debug release of dgvoodoo to the game and also enable max debug level, then download DebugView++ and make sure it's running, after that run the game and proceed until you get into the first level. Quit the game and check DebugView's window.
Check the lower traces (they're listed by time) and you see which D3D interfaces are used.
Usually only D3D2-6 games require this much work. Most D3D7-9 games can be determined simply by checking which dll file is accessed, d3dim700.dll, d3d8.dll, or d3d9.dll.