Siege of Treboulain. It's bad. At making sense, at least. But probably fine in general as far as Mary Sues go.
1. City-state. Festive day. Suddenly, a grand horde of tatars lays seige to the city! Spies? Refugees? Them recently going on conquests? No? No. Tatars got very fast horses.
2. Also suddenly, a whole tatar-hired merc fleet pulls in and blockades the port! Spies? Maritime passerbys? No. Ships are also, apparently, very fast.
3. Sometime later, throne room. A garishly dressed foreigner strides in along with his honor guard. Claims that he is next in line to the throne, so if something happens... *wink* *wink* He is. Hardly anybody knows a prominent heir, much less queen herself. Later it transpires that he
has an ostentatious mansion inside city itself. Fucking nobody knows about who owns it.
Also later, main chatacter wonders if she should recruit an urchin magical girl as one of the spies. Nope. You don't have any. Haven't seen one even halfway through the game, must be sneaky. And you are a clueless mofo.
There is rather a lot of things that make me go "Ok, ok, author doesn't know his shit (and neither do I), moving on". But the last was just laughable.
FAKEEDIT: Biggest merchant in the city needs help to name a price of it's exported good and say "Hey, look,
those guys buy it and like it, you'll still profit much from this"? Come on.
EDIT: And of course, an MC that never even touched a weapon unless strictly necessary still has to fight a hulking superpowered monster of a dark overlord in single combat and win.
Angry EDIT: In Telltale Games fashion, saving or not saving somebody ultimately doesn't matter. Like saving that oddly powerful magical girl midway through the game. She would be mighty useful in a given situation, right? And such talent needs to be preserved anyways, right? Totally worth own eye, right?
After that, she is never mentioned again until epilogue. Neither is the eye. It was inevitable.