The theme for the RPG Blog Carnival in February are the not so famous RPG system:
This month of February I invite you to gather round the campfire with your obscure indie rpgs and your sleeper hits and your imported foreign rpgs with funny dice. I invite you to gush about your love for these less well-known games, create homebrew content and share it, or tell a story about a session you where in playing these games. I invite you to pimp out your favorite roleplaying game, the one you could never find players for and settled for DND even though you really wanted to play Paranoia or Call of Cthulu.
I don't play fantasy RPGs, so at time I feel like that makes me a freak and I'm always thrilled to find blogs who talks about games that are not DnD or Pathfinder.
It doesn't really qualify as obscure, but I think that Deadlands is getting not nearly enough love from the roleplaying community. With its mix of alternate history, all the Western tropes you could want and bit of magic and monsters thrown into the mix, it's tons of fun. You can play it straight, you can add a bit of weirdness to your game or you can go full out WTF is happening. Anyone who has ever seen a Sergio Leone or John Wayne movie immediately gets into the mood of the setting (and there are so many awesome soundtracks to use as background music). Plus, you get to use just about all your dice, from d6 to d20.
Endland definitely qualifies as obscure because it's a German RPG and there is no translation. And even in Germany, not many people play it or even know it. But it's brilliant and very versatile. Playing in a post-apocalyptic world on a continent that is eaten away by fire on the one side and ice on the other, you can set your campaign anywhere from Mad Max to medieval fantasy with tech elements or just somewhere in between. The world is only described broadly, so everything else is up to the GM and I love that because it gives me a lot of freedom. You can download the rulebook for free at the Endland homepage - even if you don't read German, take a look at the artwork, it gets the mood of the game across fairly well. My campaign is on Obsidian Portal and there's some info about the world of Endland in English there.
And then there's Alternity. I played this game only for a very short time and I remember that it was a lot of fun...but I'm a bit hazy about things like rules or game mechanics. I'd love to play it again just to see if it is as good as I remember it to be.