Playing RPGs as a hobby was pretty obscure back in the day, but I’m glad it’s becoming less so these days. Or maybe it is still obscure, but the geeky media that I’m attuned to has taken a shine to Dungeons & Dragons these past years. Certainly the release of 5th edition did a lot to pull in new crowds and generate media attention! I’m glad this is the case, because it enables more people to discover the joy of RPGs!
As for obscure RPGs… I think the most obscure RPG I have in my collection is Darkurthe Legends, a so-called “fantasy heartbreaker“. I participated in the playtest with a group, which is how I ended up with the book.
I also had a T-shirt from the playtest, with a horned skull on the front and the cities where the “World Tour” went (everywhere there was a playtest group). For years, people thought this was of a really obscure hardrock group… Sadly, the T-shirt disintegrated through repeated wear and I had to throw it out.