Canadamus Prime said:
More or less, yeah.
So to that end I would ask, since I haven't played SCII, is the plot of the story distorted to force us to be invested in Kerrigan? Are all the other characters shoved to the side in favour of Kerrigan? 'Cause if not then she's not a Sue. She could still be poorly written however.
Eh...sorta yes, sorta no. Starting in a series of sidequests in Wings of Liberty, Kerrigan was presented as the most singularly important character in the galaxy (if not universe). Zeratul shows Raynor a possible future wherein the villain (Amon) is able to wipe out everyone because Kerrigan was killed in that timeline. And I don't mean that in the sense of "they needed to rally their forces", I mean that her existence is presented as the only possible point of failure for the villain. The overmind infesting her was recast from it creating an ultimate weapon to a desperate and heroic act of defiance against the true big bad of the franchise. In the final sidemission, we even have this spelled out to us by the villain himself. To quote: "Foolish, prideful children...There was one among you who could have jeopardized my great plan... but in your recklessness ? you mistook her for the true threat!" Ultimately this culminates in Legacy of the Void where she ascends to become Xel'Naga and defeat Amon.
It's a bit of a curveball, to say the least, when the games start telling you that the self-styled "queen ***** of the universe" is in actuality Space-Jesus who will save us all from destruction and eternal darkness, and that most of her bad things she did were really because the bad guy (Amon, not the Zerg unleashing her Id) was subtly influencing her behind the scenes.
On the other hand, however, if you take away the "Kerrigan our Messiah, who will be Xel'Naga" part, I'd say that she's at least a reasonably well realized character.