Saede's right here, I think.
A character is a Mary Sue based upon the artistic choices of the player-author. Mary Sue-isms provided by the gameworld itself involve no decision by the player-author. Capsuleers have immense wealth and are vastly superior to baseliners in space combat. This is the state of the lore, and not any conscious decision by a player-author when writing up their character.
(Admittedly, some players more gleefully embrace this aspect of the lore than others.)
I'm still interested in the influence of a universe of Mary Sues, where the lore is such that a player-character by default takes up many of the qualities which define a Mary Sue in other settings. I'm curious about the commonality of the archetype in, say, City of Heroes.
But since a Mary Sue is, by definition, the intrusion of the author's self and wish-fulfilling aspirations into the character, it's truly only the player-author's choices that matter in testing for a Mary Sue.