Ask HN: Summer coding challenges for Pre-Teens?

I have an 11 year old son that loves programming. He’s really into game development and has a decent handle on Unity, C#, Java w/ LWJGL, python/pygame and a bit of JavaScript. He’s good at reading tutorials and exploring, but I would like to have him be able to work on a full project. Are there any good programs out there for precocious programmer kids? Emphasis on kid; I’m kinda keen on him having a little bit more time for childhood innocence...