Add one small twist

Once you are inside their game, you have earned one idea. Make it small and make it a question or a problem, not a correction: "Oh no, the bridge is broken. How will the cars get across?"

A good twist stretches the game a little: one more step, one new problem, one surprise the child can solve. Then hand it straight back. If they ignore your twist, let it go; it was theirs to take.

One twist per game is plenty. A grown-up who adds five ideas has quietly taken over again.