Assuming we're allowed to post unpublished Sues.
Early in around 2011-2012, I stumbled upon this website. If you don't want to click it, basically it's a bunch of comics that are set in a school AU of Plants vs. Zombies with different character personalities. (Due to the "species" argument, where each plant in the game is in fact only representative of tens, hundreds, perhaps thousands of a species like them, it's not a replacement.)
Of course, MS Paint and having a bunch of those kinds of kids at the wheel don't get you very far at all.
Unfortunately for me, I did not know what cringe was and I also happened to conveniently be a part of the demographic I just mentioned. So I treated it like it was some big media production, cooking up some incredibly wicked fantasies, including an implausible crossover between an AU already going straight to hell and mechs from mecha anime. ...Yeah.
If I didn't renounce my status as a fan of the genre for years I would've become a stereotypical weeb, I'm sure of it.
I'm not even ready to type the fullest of my memories up a second time, so I'll just copy-paste a few bits from the first time I did.
- "I would seriously imagine each character as holding on to a weapon, item, etc. up to and (mostly!) including downscaled fully functional mechs (which I imagined as suits/transformations) from mecha anime and games.
I would then proceed to beef up the original mechs as much as possible." Surprisingly enough, this actually makes the most sense for how it came to be since this is pretty much what most badfic written by a child is.
- "The Mary Sue approach to death. Die, friends mope a bit ton, five days later they're back and everyone acts like it'd been five years, not five days." I treated the "depressing" points of the AU like the ultimate edgelord. Don't get me wrong, I still do that sometimes, but at least I have some better judgement in playing it out.
- In short, I also wound up creating replacements of the entire cast. Eventually, the multiverse kitchen sink bug hit, with Minecraft taking the lead by a huge margin. I had basically developed at least five different versions of myself, with no variety. (I'm trying to write two agents right now that are supposed to be this but with actual variety. One's the snobby, hot-blooded-but-weak-minded kid and the other's the more judgmental, realist individual. I sort of have to balance these two major personality factors as one whole every day.)
And there you have it. Of all the Mary Sues in the world, nothing can really top what children wind up making. It's just that none of their "brainchildren" (including mine) have surfaced on the internet until now...