Globe and Mail posts a lengthy and unusual Q&A with AC2 director Benoit Lambert on the nuts and bolts of developing a game's level of difficulty. Says Mr. Lambert:
"...But what does difficulty mean? What is a challenge? How can you ensure fun when it comes to difficulty?
Let's forget about games for a couple of minutes and remind ourselves of the first time we rode a bicycle. If you learned how to ride a bicycle properly, if you were trained using a tricycle, if you encountered some success for the first few metres you were riding, then you will want to ride more. You will feel you are progressing and you will expect to continue experiencing new emotions and new challenges.
Similarly, Assassin's Creed 2 is all about learning. You are becoming someone you are not: The best assassin there is. It is true not only for the main character, who is by no means an assassin at first, but also for the player (I hope). The game design, the story, the environment...everything steers toward this objective of allowing the player to properly learn, receive rewards, and face new and adapted challenges..."