As an amateur game designer (nothing published, and if I ever did it would be free and targeted at educational environments- for example, I used Sid Sackson's Card Stock Market to help teach numeracy) I recommend sticking with tactile materials rather than computers, let alone 3D. For any age, but especially while young, to build those physical-mental connections. Computers are great diversions but they require such a deep infrastructure that I doubt they'll last very long.