"Der kleine ICE," a game app from German Federal Railway

Speaking of trains, J loves the app "Der kleine ICE" from the Deutsche Bundesbahn and has spent many hours over the last year and a half playing it. 

Basically you build track connecting cities in Germany, then drive your train from city to city picking up passengers and dropping them off. As you accumulate points, your character gets nicer uniform bits and your trains get faster and more elaborate:

For education purposes, a child can learn a lot about basic German geography. Where the big cities are and the names of the rivers: 

I personally have not spent a great deal of time with J on such things; he has learned them from the game, and when in some other context he hears the name of a German city, he will often say that he has "gone there in the ICE game." 

For L2 purposes, there is a nice clear voice-over speaking the directions and other little commentaries. For the more advanced child the language part is not terribly rich, but it does work the idiomatic German prepositions for travel von ____ nach ____. After he began playing this game, I noticed a measurable decrease in J's propensity to say von ____ zu _____ when speaking of travel.