Varianor Abroad
Explorer
It sounds interesting. As someone DMing for a 9 year old, and looking into stuff for games for Gen Con next year, I'd check something like that out. My answers in no way constitute a mandate or a guarantee of any sales of course. 
The "over 18" disappearance of course hearkens to Logan's Run, where in the novel anyone over 21 was forcibly disappeared. I think in the movie they made it 18. Your setting sounds nothing like that of otherwise.
I suspect the challenge you face of course is that there are just so many settings. Mind you, it might have some ability to break through the noise for parents, since it has a specific focus.

The "over 18" disappearance of course hearkens to Logan's Run, where in the novel anyone over 21 was forcibly disappeared. I think in the movie they made it 18. Your setting sounds nothing like that of otherwise.
I suspect the challenge you face of course is that there are just so many settings. Mind you, it might have some ability to break through the noise for parents, since it has a specific focus.