Two players, one phone
Family duel
Five questions. You and your child take turns on the same phone. Neither of you sees the other's answer until you have both had a go.
Who is playing?
Five questions, one phone. You take turns, and neither of you sees the other's answer until you have both had a go.
No copying
The first answer stays hidden until the second one is locked in.
Ten minutes
Short enough to do after dinner, on a school night.
They usually win
And that is exactly why it works.
A word to the grown-up: do not go easy on purpose. Children can always tell, and a win they were handed is worth nothing to them. Play properly and lose honestly — that is the version they will want to play again tomorrow.