Each game in the HoMM series is remarkable for adding to the gameplay, the complexity and the richness of the original idea while preserving the basic playability and worthwhile strategy elements found nearly a decade ago (in the games' ancestor "King's Bounty"). It's extremely rare to find  a sequel that improves on the original =without= rendering them obsolete.  (HoMM I and HoMM II are today almost as playable as this game, lacking only  the polish and convenience that comes from so many years of refinement.)  This is only achieved by making the game different enough so that you have  to change or refine your thinking about it.