The greatest ever. I'd buy stock. You are secretly learning algebra without realizing it's educational.. Just do it. Skip the trial since you'll have to repeat the levels when you buy the real one...and you WILL buy it. It's just that good. Bought it to brush up before my kindergartener gets to algebra, and not only is it reteaching me, it's teaching him too, and it's reframing a subject I've hated and made me become an algebra game addict. Kids week learn to love algebra way before school gets to make him hate it. My only COMPLAINT is that the opposite/night cards don't look opposite enough. They should be more obviously the same thing, just negative. As it is, it took awhile for us to always see the correct opposite card. But the whole series is fab. We just bought the new numbers game, way below algebra, but still cool.