(Since someone already mentioned bedrocklinux, I’ll try harder)

… Try putting the Ironclad kernel in Exherbo. ;D

I see no one has mentioned Bedrock Linux yet. Not sure though how others would rate its ‘obscurity’ though. It’s definitely a standout among distros.

No one mentioned Bunsenlabs or Crunchbang Linux here, but they aren’t really that obscure.

Linux STD! Waaaay before skiddos had backtrack or kali

The first one that came to mind was fli4l (Floppy ISDN for Linux). Originally a distro of German origin that fit on a single floppy disk to turn a 386 or 486 PC into a router for ISDN connections. Last I looked it’s still actively worked on.

There are probably tons of more obsuce ones. But this is one I actually used.

There was this distro that stuffs everything of a package in one folder, instead of /usr/lib & co. What was it called again?