I'd start with Scratch. Lots of well meaning advice here but Scratch is still the best for kids to build code and quickly see the product dance on the screen. Q

I'd start with Scratch. Lots of well meaning advice here but Scratch is still the best for kids to build code and quickly see the product dance on the screen. Quick iteration time is the key to building a feelings of accomplishment. We started with the book "Scratch Programming Playground" by Al Sweigart. Now we are doing youtube tutorials by Griffpatch. One of the latest is a simple 3D raycast Wolfenstein clone, which might interest your son. However I recommend a simpler jumping on point, like his Geometry Dash series: https://www.youtube.com/playlist?list=PLy4zsTUHwGJJnoXPSYlKQ15wedqB39W_E https://www.youtube.com/playlist?list=PLy4zsTUHwGJJnoXPSYlKQ...