I haven't played a lot of TTRPGs yet, just a few, but currently, my favorite one is Aquelarre! It's somewhat unknown since it's almost only played in my country, Spain. It's based on the spanish medieval ages (though it can be easily applied to any other european country and there are supplements to do so) with low-fantasy, as in, magic is extremely hard to learn and use and it's users are few and hidden, and the bestiary is based on mythological folklore creatures of the region!