Thank you for your kind words! I'm glad you learned something about mushrooms lol. When I first started working on this game, I didn't have the mushroom theme planned. I ended up drawing Muscaria after Virosa and realized "Wait, a mushroom theme would be really cool!" and just went with it. Important to note is that amanita muscaria has hallucinogenic properties, which aligns with Muscaria's declining sanity.
Yeah, the main complaint I've had is about the font. Which is understandable, because I hate how the I looks too. I think I can change it to another Delius font for the next game.
There's no real symbolism behind the blue shirt. The red shirt is important because of the connotations related to red (like violence, blood, etc.) which represents the hero's play style. But it also connects Muscaria and Virosa, because they gave her an "muscaria" colored shirt. It just kind of represents that they both need each other; Muscaria because Virosa is the only reason they're alive, and Virosa because she wouldn't have been able to progress in the game without this shop.
Virosa's mushroom form is symbolic and not something that actually happened. Muscaria perceived her in this monstrous form partially because of their mental state and worsening perception of her, and because Virosa's way of playing the game turned her into a worse "monster" than the actual enemies. It's symbolic of how players can do horrible things in video games, to the point of seeming worse than the antagonists. So yeah, Virosa never actually turned into a mushroom monster.