Here's a VERY simple 3d program I've made. It's Free-Ware.
You can Down-Load It Here!
It's features :
Flat grid-based square map
Texture mapped ground and sky
6 Degrees of freedom
Extreme Slowness (.05 FPS on a 486/66Mhz)
Distance fading on the ground and sky
-=-=-That's about it-=-=-
The next 3d project i'm going to try will probably be voxel mapping, because
that produces very much more interesting landscapes.