Comentario Slashdot /. Incluye el juego "Tranquilidad"
Here's the educative games I suggest.
http://www.food-force.com/ Made by the U.N. Free, MacOS X or Windows. (sorry no Linux afaik) Probably the best one in my list for the 6-8 years old.
http://www.tqworld.com/ - Tranquility. After years and years, this game has something no other game offers. Well suited for the youngsters. Free, but not open source.
http://www.stopdisastersgame.org/ U.N. too. Free and web-based. Excellent. Probably best for 8 years old (older ones of your range). Surprisingly informative.
http://www.stepmania.com/ Not sure that ones counts as edutainment, but it sure is good for the children! Open source and available for all platforms.
http://www.openttd.org/ A railroad tycoon open source clone (gosh I'm getting old