Yes, the Amazon version is only 5 levels (I looked at that too).

There are (albeit minor) penalties for incorrect answers. During the game if you make a mistake, usually another baddie will come out and attack you. During the last phase of review (Q&A) answering incorrectly will have an effect on getting bronze, silver, or gold. Knowing our DS, that works for us because he'll play and replay levels until he gets gold medals.

We're still pretty happy with our purchase. We have developed our "school year weekend routine": mornings play outside, lunch, rest time (he reads, other kids sleep), then Evolver for a little bit.

The only thing that I didn't like is that you can't save mid-mission.

Buying the game also gives you online play. I have not evaluated that yet.

JB