If your cousins have iOS devices they should check out Hopscotch. (http://gethopscotch.com) It works on iPhone and iPad and you can use it to learn to code and make your own games.
Full disclosure: I founded Hopscotch. But it's still awesome if I do say so myself :)
Hopscotch | New York, NY ONSITE| Full time Senior Product Manager
At Hopscotch, we’re reinventing programming. We believe that anyone should be able to code.
We are a small team of 8, and we pride ourselves on shipping product. Our CTO came from Pivotal Labs and we love the Pivotal process. We work hard in the office, but everyone has a life outside of work. Folks are continuously impressed with how quickly and efficiently our team gets things done.