Oh yes! Manhole Masterpiece is great for young'uns! Hard to find though.
Really good adventure-ish (purchasable) titles for that age group include Cluefinders, Humongous Entertainment games (Freddy Fish, Putt-Putt, Spyfox etc), and Dr Brain games.
& David Macaulay's "The New Way Things Work" & "Pinball Science" are especially worthy of note. They are funny and you can't get very far without learning quite a bit :D
There are many free (& educational) fun sites for kids online ~
http://kids.discovery.com/
http://www.nationalgeographic.com/kids/
http://kids.msfc.nasa.gov/
http://www.thekidzpage.com/
http://www.kidsgames.org/
http://www.funschool.com/
[url=http://www.bigidea.com]www.bigidea.com[/url]
http://www.gridclub.com/
http://www.ladybird.co.uk/
http://www.classbrain.com/
http://www.indianchild.com/educational_games_for_all.htm
But free adventure games for children are harder to find. I googled and found these possibilities
http://www.ambrosine.com/games.html
http://www.kidsdomain.com/down/
http://dmoz.org/Kids_and_Teens/Games/Computer_and_Video/Demos_and_Free_Downloads/
Hope something on here is helpful!
Susan :wave: