Damn this looks like fun:
https://youtu.be/10f1Mvqs9Z4
It's called Tiny Dungeon, and it's kid-focused, without dumbing things down too much. Pretty rules light.
Available here:
https://shop.gallantknightgames.com/col ... nd-edition
Also there is a "Wastelands" variant (read: FALLOUT! WANT!) and a bunch of others. Also at DriveThruRPG. You can get these as hardcover, softcover, PDF, or combination of print/digital.