My son is in the same age group. These are some notes for what worked well for him. Godot and Gamermaker are great because they have loads of tutorials on YT.

My son is in the same age group. These are some notes for what worked well for him. Godot and Gamermaker are great because they have loads of tutorials on YT. He can sit down and work through those pretty comfortably. These work better than Unity \ Unreal because those have so much to learn and a long time before you have something playable and many tutorials would switch out to an IDE and had loads of files which overwhelmed him. He started with Scratch and built up to some pretty complex gameplay. What's nice with this is that he was able to remix existing games he liked that others have published. This meant he learned more as he modified. Checkout griffpatch on YT for the more complex stuff.