Did you really think so? I can't remember where DF started, so I'm going to have to be careful with spoilers but in my view, the "game characters" were either humans (professor Ye if I remember well), or weak AI game characters programmed by the Trisolarians in an attempt to map their propaganda to humans. The game itself is an information operation: it is designed to cultivate a resistance within humanity and disinform humans psychologically in order to gain yet another edge over them militarily.
However Trisolarians themselves are a "superior civilisation" which is both helped and hindered by a particular feature of theirs which we don't have (related to the Tines, actually) and which becomes the core plot point enabling most of DF to play out (like the Wall Facer project). Sophons are just sophisticated communication devices, there to send back information to Trisolarians so they can better understand, hinder and later destroy Earth; they are not themselves strong AI (and therefore not a civilisation).
Thus what makes it interesting is the game theoretic aspect of it, and especially the treatment of information flow. Trisolarians know everything except the thoughts of humans (and, initially, they also lack the information that humans are capable of private thought).
It is not what they say (which is purposely adapted to look human) but how they react to learning bits of information that makes them a fully fleshed out alien culture (such as learning abstract concepts like deception, then figuring out the game theory of deception and altering their conversation onto the ETO accordingly).
The human fifth column goes from being a convenient tool of further aggression, to a core path to avoiding the one realistic chance humans have against the invasion. The ability of the Trisolarians to create a high quality "virtual machine of human minds" within their civilisation capable of such manipulation makes them a convincing "higher civilisation" (which is what will make the third book interesting, I bet, especially after the closure brought by DF).