One thing that really added to the fun when they were making games is I got a PS3 controller (which is bluetooth) and connected that to the computer as a keyboard, which Scratch code can then read and use in the games.
The first big (for them) project we did was: https://scratch.mit.edu/projects/219423211/ They had just turned 7 and 9 when we did that and dad helped them out with a fair bit of guidance (and cribbing from other projects), but after this one, they really took to playing around with it on their own and a few times per month, I'll look over and see Adam using scratch around 5 years later.
PS: There is a Scratch Jr if your kids don't seem quite old enough to have the attention span/focus for scratch.
They do a lot of Minecraft now but are interested in TinkerCAD, which I’ll solidify by printing some of their designs. Not sure any of the beginner CAD apps are really easy, though.