MAKE SURE YOU READ THE PRODUCT DESCRIPTION BECAUSE THIS IS A GAME THAT IS DESIGNED FOR USE WITH OR BY YOUNG CHILDREN. Children of 10+ may well find it too easy - but as a way of encouraging much younger children to want to explore a mysterious land and to solve interesting and thought-provoking challenges, it is hard to beat.
This is a superb program based on the principle of problem-solving and interesting challenges in a world which has nothing to do with endless shooting or killing. Neither it is dumbed down like so many so-called 'educational' programs.
I used to use an earlier version of Crystal Rainforest with early-years primary pupils and they loved it. The program encouraged lots of meaningful and excited discussions which parents or grandparents can now experience with their own children. Based on my own experience, I think this program works best with children in the 7-9 age range, but 5-6 year olds will also enjoy it with guidance from an adult or older friend.
Many of the puzzles are based on the Logo programming language but don't worry if you are unfamiliar with that - it's structure is built into the heart of the puzzles so that it's those that entertain your imagination.
I recommend hat you ignore the reviewer who awarded just 2 stars on the basis of his own child's boredom --- I can only think that user must have ignored the product description.
One additional comment ... if you become interested in exploring Logo itself, there are several commercial programs available but the one I used to use in schools in a Logo club is totally free. I could therefore use it in school and also give copies to pupils to use at home. Just search the internet for MSWLogo and you'll find it. It isn't a flashy program, it's pure Logo.