How much time do you have?
That said, the implementation of each of these many levels seems a little under-cooked. I played it constantly for a few weeks, and realized that my enthusiasm was mostly in discovering the range of stuff that's jammed into it. After that, the repetition—things like performing a repair task on the city gates 10 times in order to get the defenses back up, which is 100 days in game time—started getting to me and I haven't played much. Another example of that is that in the first week or two I fought every battle manually, but set that aspect of the game to auto thereafter.
Still, the subject matter is incredibly rich and interesting, and it can easily keep you occupied well beyond your intentions... I have become so interested in the Three Kingdoms through this game that I am now reading the original "historical novel" (unabridged!).