I have been really impressed with this product. It seems so simple, but my children enjoy it and are learning from it. We downloaded a few of their products for this review. My children's favorite has been the Whole Number Fun. They are grades 1, 2, 4, and 9. They say it is challenging but fun! They like to do lots of problems so that they can earn robots (and I believe some other things, but I am not sure what) to give them "lives" to play some of the simple (think Atari) like games. My children love them. This supplies motivation (complete and get the answers correct) to do the math problems so they get to have fun.
These games lack sound, but that has not been an issue for us. They do look simple, but my children really enjoy the games and doing the math problems. They will play this for hours at a time, if I let them.
These programs are available from early math through algebra. They seem to have similar formats. These are available for $24.95 including shipping. Also available are PDF format e-books for each series that you can print out.
Lots to preview on the website - go take a look by clicking HERE.