this was really short, and really good!
it's a super simple game but that's what makes it effective. it gives exactly the right amount of information the player needs to be engaged with the story, and leaves everything else to the imagination, to great effect. each ending is more disturbing than the last, culminating in a sad but powerful true ending that gives a little more insight into what's really happening. and once again the art is really good, increasing both the charming personality of mary and the sheer horror of her and lamby's different fates.
like in the first game, the wording in a lot of parts is a little off but again, i'm not gonna rag on that. and something i actually think was improved over the first game is the storytelling! your "let the players draw their own conclusions" way of writing worked even better in a shorter & simpler experience, giving out the right amount of lore to keep us intrigued.
in fact, in you don't mind, i'm gonna give my interpretation of the story of both games! i'm probably mega wrong but i'll do my best lol:
(SPOILERS FOR THIS GAME AND THE PREVIOUS ONE, BORROWED BOOK)
i think the microorganisms world doesn't actually exist. it's some sort of fantasy world people who have suffered severe trauma go to, to escape from reality. and both rudy and mary are counterparts of their real selves.
in Borrowed Book, megu is someone from the real world that, with some kind of advanced technology (the "simulation"), enters the mind of rudy's human counterpart in order to fix the trauma that left him severely mentally scarred and gave him amnesia. all the spirits and creatures they meet in the library represent different parts of rudy's fractured psyche: the spirit that asks you to find a book and leaves behind a note about a mother (rudy could be obsessed with feeling like a "reject", and his mother maybe played a part in his trauma), the spirit that fake-kills a doll (maybe rudy murdered someone in the real world?), the wall of flesh that gives you a quiz (the dialogue if you fail all questions proves his desire to fit in)... while all this time, megu is lying to rudy, telling him that she's his guide and that she's a microorganism too, which rudy almost realizes as the last spirit asks him who does he trust in. it's all an attempt to fix his psychological state, shattered by some horrible thing that happened to him in his childhood (evidenced by the drawings screens near the end of the game, which give off the vibe of a twisted childhood home).
in Mary Had A Lost Lamb, mary is also the counterpart of a real girl, who suffered greatly from losing her dog at a young age. each ending represents different emotions she felt by that loss: the tree ending is her desire to find her dog again and be together forever, the rifle ending is her longlasting anger at him for leaving her behind, and the god fusion ending... i don't really know what that meant, i'm too dumb to get it lol. however, as we see in the true ending, mary (or marie) has a better grasp on reality that rudy, as she's able to go in and out of the fantasy microorganisms world. also in the end, lamby (or lance) maybe comes back? i'm not sure if that actually happened or not.
so yeah, that was my reading of everything! i know the "it was all a dream/trauma-induced fantasy" interpretations aren't super original but it's what i came up with lol.
in conclusion, really good game!!