A game as enthralling as the first! The only things... and I stress: the ~only~ things that hold me back from a total of 5 stars is... there is no real storyline, and you're rather limited in the beginning. . The music is simple, yet doesn't seem to get stale. The graphics are a labor of love (always more of hindsight in strategy games - for reasons of brevity). The gameplay and strategy are thoroughly engaging.
Yet... I feel no real identity as a player. There is no driving reason to want to see the story through to the end. In the beginning scenarios (replayed), you can't really level-up like you have in the conquered levels in the future. IMHO: Once you have achieved the ability to do something, you should be able to accomplish it at any re-played level of the game... sort of like the dejected would-be overlord coming back to wreak his revenge.
Without a story, the gameplay really means nothing to me. Without some kind of emotional appeal (no matter how twisted!), a game like this will break down into simple math. The staticians amongst us are thrilled by the challenge of "breaking the code" (NOT necessarily the game!) and winning the game with brutal science. The emotional players have nothing to grasp that compels them to see the game through to its end. Give us a story, and make us the star, and you'll get the remaining star from me.