Ask HN: Are there any fun games found on the iPad or iOS that teach programming?

I have two younger cousins who are extremely interested in what I do -- building webapps. I've taught them how to make simple static pages. I think they have the capacity to learn much more, but I can't always be there to show them new and exciting things. They're glued to their iPads.

Anybody here familiar with applications designed to teach the younger generation, in a fun way, how to program and/or the fundamentals needed to think like a programmer on the iPad?