There’s a certain vocabulary in the Batman fan community, a dialogue made up of stories that everyone recognizes, with an acknowledgment of common reverence that need not be spoken.
Few need to explain what they thought of The Dark Knight Returns, or ask about The Long Halloween. It is simply understood that one should know of these stories and their significance, as such tales are the seminal books of Batman.
It’s not often that outside media enters in to this exclusive lexicon, where respect and adoration are implied merely through reference. If one talks about Burton’s 1989 film, it is not simply assumed that he speaks of it with approval.
Those outside properties that have entered this elite class, such as The Dark Knight and Batman: The Animated Series (so revered that its original ideas bled into the comics for years) succeeded in the same way that Arkham City does: by being more than a mere cipher for the source material.