My sisters, friends and I used to spend so much time on this when we were about knee high.
And all our parents, after having a quick look practically endorsed it!!
Even an e-mail pen pal from Canada that my school set me up with in 1994 (I was 7) had it. Blew my mind!!
I only got hold of Treasure Mountain later. As a kid I remember borrowing Treasure Cove
and Treasure Math Storm from a friend. They're all part of the Super Solvers Collection.