Zonyx was created as an experimental proper-3D version of Zaxxon (as opposed to isometric)
It runs with a fixed 320 x 256 pixel resolution that is scaled up when displayed.
It's for Windows only - written on Windows 7, but tested on Windows 10 as well.
Written partly in BBC Basic for Windows with a DLL in C for drawing the graphics.
Triangles and spheres are plotted pixel by pixel, which allows the z-depth of each pixel to be calculated with a bit of ray tracing; some texture mapping can be done and a display depth-map is maintained.
(The depth map also enables pixel-perfect mouse-over-object identification, although that isn't used here.)
The 3D nets can incorporate additional lines used for simplified collision checking. Drawing an environment is one thing - interactions with it is another.
Sound is minimal using the 4 channels and ENVELOPE command built into BB4W.
I've always been fascinated with 3D environments ever since 'Elite' came out on the BBC Micro, but I'm a very slow learner! I also can't draw for toffee.

Zonyx zip folder stored on Google Drive - yes, it really is that small