But, to get off my soap box and answer your question... My first computer game favorites were things like Kid Pix when I was at school, or Sim City when I was at home. Those somehow seemed really fun to me at that time.

Not that I would know first hand with my moderate level of kid experience, but I bet for younger kids the things that would draw them in most are things that would be easy to manipulate and would show instant gratification from actions made. They make a change in something on Sim City and immediately see changes happening on the screen, or something like that...