Follow up to: Rationality Games Apps

In the spirit of: Games for rationalists

My son (10) wants a smartphone and I reasonably expect that he wants to and will play games with it. He appears to be the right age to use it. I don't want to prevent him from playing games nor do I think that possible or helpful. But I'd like to suggest and promote a few apps and games that *are* helpful or from which he can learn something.

Obvious candidates are

There are lots of low profile apps filed under learning in the app stores but most of this is crap and it takes lots of time to explore these.

I also found some recommendation for learning with Android apps and will point my son to these.

I'd like to hear what apps do you or yours children use. Which apps and esp. games do you recommend for future rationalists?