I've seen computer games where any input device is accepted, and on-screen instructions refer to the last type of device used. Seemed like a good idea. And how does input-based parental control work? Do you hide the adult's controller?
the case for physical games: put the cartridge on the high shelf
If you've got a child in the household, you're expected to tag their user as such, which imposes some restrictions on their account. Then set up an access code on your user, so the child can't log in as you.