If you're curious about whether Ooka Island is a good fit for your child, consider the free 14-day trial.
My child is reading on what I think is a first grade level and I had hoped that the games would help fill in any foundational gaps for her to help her move forward. As she played, the games and tasks were too easy for her and her willingness to play quickly disappeared. If you are not sure about your child's developmental range, utilize the free trial to get a feel for what kind of match Ooka Island is for your child. It might be perfect!
My girl has been sounding out unfamiliar words with more accuracy (she has amazed me several times in recent weeks) and I do think that Ooka Island has played a part in that.
Sometimes, we get a product with a recommended age range that seems too young or too mature for what the company recommends. In this case, I think that the Ooka Island folks are spot on - this is for children who are between 3 and 7 or who are developmentally within that age range. (And I suspect my girl is reading a little bit above where I think she is.)
My one caution is to please check the system requirements against your computer. The download /setup is big and took longer than most downloads.
We were given access to Ooka Island in a six-month subscription to use and review here. I was not paid for this review and am not obligated to provide a positive review.