If you are reading comments wondering if you should try this... TRY IT.
I heard about this on the Dungeons and Daddies podcast. Not only was this was perfect game for me to try out gm'ing, it was the perfect game for my friends to try ttrpg for the first time. It's very simple, takes minutes to setup and can be improvised on the fly. You get some guide rails to work within but it is ultimately wide open for you to create your own story.
I gm'd for two rats and had a blast.