This is going to be very opinionated advice. It might miss context, it might miss nuances but I know I'd do it and execute on it immediately.
Use Unity3D.
Specifically: hack a prototype together on your own in order to get your bearings a bit. Then, do it together with him.
If you want, we can also create a small Unity3D game together because it sounds like fun and I have not been doing that for the past 10 years.
When it comes to teaching programming, you want an interactive programming language. Like, JavaScript in Chrome dev tools is interactive or Pharo is interactive (though Pharo is niche so wouldn't recommend as a first language). Hooking up a debugger to a program makes any language more interactive.
[2] Wind Hockey (in Unity3D took 50 hours not knowing anything about Unity3D before that other than one basic lecture of 60 min. at uni): https://www.youtube.com/watch?v=qTIZ-_UFXqQ
Use Unity3D.
Specifically: hack a prototype together on your own in order to get your bearings a bit. Then, do it together with him.
If you want, we can also create a small Unity3D game together because it sounds like fun and I have not been doing that for the past 10 years.
When it comes to teaching programming, you want an interactive programming language. Like, JavaScript in Chrome dev tools is interactive or Pharo is interactive (though Pharo is niche so wouldn't recommend as a first language). Hooking up a debugger to a program makes any language more interactive.
Some stuff I made back in the day:
[1] A computer graphics engine (as someone mathematically challenged, haha): https://www.youtube.com/watch?v=PH6-dLvZEiA&pp=ygUMbWVsdmluI...
[2] Wind Hockey (in Unity3D took 50 hours not knowing anything about Unity3D before that other than one basic lecture of 60 min. at uni): https://www.youtube.com/watch?v=qTIZ-_UFXqQ