Assassin's Creed III is coming out later this year and once again it's ready to trump the last game with various improvements and novelties. When seeing and playing the maiden game of the series, we were impressed, but look at it now!
There has always been an increasing importance on realism in gaming environments especially for actions games of a high console calibre. For continually successful titles such as Assassin's Creed, I'm guessing a lot of the budget goes into the artistic, phenomenal feel of the places you play within. Keeping in mind that the premise of the Assassin's Creed story is that you are reliving a past time to save the world, etc etc, it makes sense to have this emphasis on resemblance.
What impresses me is that all of these highly complex environments are based on real historical settings outside of any living person's real experience. Calling upon a tonne of research and a vivid dose of imagination, the game creators take on this challenge. Now, with the new AnvilNext (hope it's a developer's inside joke because it's not a catchy name..) game engine, apparently they're taking weather conditions, landscaping and atmospherics to the next level. They'll need a lot of that in colonial America - past Assassin's Creed games focussed on the Middle East, Florence and the ancient lands of Rome in it's heyday - filthy rich with elaborate, historically primed architecture and cities. Baby Colonial America wasn't even on the map yet.