That sounds a bit scary to me. Substitute gaming with gambling and you will get an idea. Do you want your kids (if you happen to have any) to go to a casino?
If you play with fire, you're gonna get burned
actually i was talking about gaming(and i don't like gambling too) that don't bring money but can teach them what bitcoin is
something like a puzzle that when solved reveal a private key? could be fun
I am sure that once the kids get hold of the private keys, they will be no longer interested in gaming "for fun" (having understood what they are used for) and quickly switch to chasing after your private keys, since it will be real fun (with all ensuing consequences)...
about the coins before it is better to tell them that they need to focus on the real money instead of bitcoins.