I'm a sorta professional DM and have done some tabletop design so I'm probably in the pickiest possible audience for this, but I gave it an earnest shot and it didn't land for me. Story wise I was intrigued but it seemed like you just dropped the things you were bringing that made stuff unique. Like, I could imagine the first part of the book being full of color, but the later parts of the book could conspicuously be more and more greyed out. That kind of thing. I was hoping for more exploration of why the situation was what it was and the answer to not just be the equivalent of a wizard did it.
Biggest issue though is that there's some fundamental design issues with the combat. If a battle system has deterministic damage of "atk-def = damage dealt" then there has to be some mitigating factor that introduces randomness, or the defense can never equal or exceed attack values. With infinitely respawning rats, who can't possibly harm a player who has 2 defense, as long as the player buys a sharp stick and a tunic in town at the start they basically can justify to themselves just assuming they have infinite gold - the dice rolling is just busywork when the outcome is already predetermined. And until a player buys a sharp stick, they literally can't harm the rat whatsoever.
The only combat that actually requires dice to be involved at any point, then, is the final one. but 50% chance to do damage, 50% chance to be hit, then 50% chance to get loot... it's just not engaging. I dunno why clicking buttons to do the exact same thing feels more enjoyable to people - with an MMO you've got the visual stimulation and the appeal of the social aspect. Even simpler board games give you a tactile thing to interact with and maneuver around a board.
I think even the simplest fix (attacks do a minimum of one damage no matter what defense) would improve things quite a bit, but the rules around the combat loop are pretty unclear - do you lose anything when you die besides time? If the only punishment is time, you again run into the problem of the player knowing they're guaranteed to get infinite gold if they just roll the dice enough, so the motivation to play things out falls significantly. The burgeoning solo game genre is pretty fascinating to see what designs work - there are games like Gloomhaven and 7th Continent and Onirim and some dungeon crawly puzzle-books whose names escape me that have proven there is a market for solo tabletop style games. At the end of the day those all come with one thing: the core gameplay loop has indeterminate outcomes, and feel like solving some kind of puzzle.
You mention at the end that you're not sure it's the type of game for you. It's really good to stretch one's design legs and try genres they don't think are for them, but imo if you don't like your game by the end of it, probably something went wrong along the way. I think it's ambitious and cool to try something like this for this jam, even if I don't think it really worked :)