There is none, ENIGMA is compiled directly to C++ using the GCC compiler, and will soon be %100 compatible with Game Maker, as well as implement extended features including GLSL shaders, entirely free and open source. We have really only made this engine for our own use, we don't want any money.
Did you not read my last sentence? That is why I suggested XNA and Visual C# if he really want's something basic to start out with. But if he really wants to learn 3D programming the real technical way (DirectX/OpenGL) I would suggest he learn OGL it is much better I think to learn with than DirectX, plus it saves him from wasting his time learning DirectX. I would start with OGL and then learn DirectX, allot of DX code is pretty archaic and it is nowhere as safe as OGL programming.
Personally I would suggest he use something like Unity3D or Game Maker, or more specifically the open source free Game Maker that I am a developer for.