I remember seeing this like 2 or so years ago and just remembering it today as "rat rpg" and i spent like 10 minutes trying to find this "rat rpg" that I remembered. Google searching things like "rat rpg" "rat rpg protagonist" "rat rpg with rats as main characters" "rat rpg where rats go to a groccery store", searching itchio for "rat rpg", "mouse rpg", and eventually searching "little mouse rpg" and finding it. (And yes, those are all google searches I made.)
The grocery store(?) scene stuck out in my memory. How the game suddenly became a horror game. How the whole world was suddenly too big. I don't remember it well - as I said, 2 years ago I found this game in a random youtube video.
Thank you for making such an interesting and compelling game and setting.