Game Builder Garage looks really interesting, thanks for the suggestion.
Do you have any experience with Dreams on PlayStation, for comparison? My son and I have been using and enjoying Dreams but I do feel that he would be better off with something a step down in terms of complexity and challenge. GBG looks like it could be the sweet spot.
I'll also highly recommend GBG. My eldest had a good time building very creative things when he was about 9, and my younger son who is 6 has built a 3d platformer. i haven't a clue how to program it, but they pick it up easily! Also, they both love Scratch (not Jr) on a browser. Not 3D, but a great outlet for their ideas.
If it's just level building, then Super Mario Maker 2 (also Switch) and Levelhead (Steam, more accessible on Switch). There's also BQM (Steam,Switch) for isometric dungeon designing.
If you have tried Dreams, I would recommend Little Big Planet. It has a game builder that is a step down from Dreams but they were both designed by the same company, Media Molecule. Not to mention LBP is just a magical game all around!
I came into this thread with the intention of recommending LBP and possibly Dreams, although the latter is a big step up in complexity. LBP lets you do wonderful, creative things in 2.5D without any coding knowledge.
But seeing GBG being mentioned, I wish I had that growing up. Looks like the perfect way to get started.
I want to second Game Builder Garage. I recently went through the tutorials in this game with my six-year-old and it's been an amazing introduction. There are also a bunch of tutorials and games you can find the codes for online if he wants to go further once done. I've haven't found anything else that simplifies 3D game making the way this did.
https://www.nintendo.com/en-ca/store/products/game-builder-g...
The app has tutorials and built in games to get him to work up to making a game.
Surely, his current game is too ambitious for him to pull off but this will get him making something and thinking about programming.
There is also RPG Maker depending on the style of game: https://www.rpgmakerweb.com/products/rpg-maker-mz is the latest, https://www.rpgmakerweb.com/products/rpg-maker-2003 is the oldest and cheapest.