I told him to get started on his own while I took care of the groceries and lunch, and then after lunch we could draw together. He went away and came back a few minutes later with this:
I got to work on construction, supervised by K, and he started drawing the game screens.
After about two hours, we ended up with this:
And here's K carrying out his plans!
I was worried X would destroy it when he got home, but instead he grabbed the other controller (we added a second one after this picture) and they played together. The only argument was over who got to be John. Finally K convinced X to be Bob instead. Bob's the one who falls down. Dave runs the other way, and John tries to use the fire extinguisher as a jetpack.