So is Hogan, apparently.

Not based, it just does the same thing.

Actually, “hogan.js is a compiler for the Mustache templating language” –from https://github.com/twitter/hogan.js

It is compiler for Mustache, it does the same thing, it passes the same tests, but they didn't take Mustache code and improve it -- which is in my opinion what being based on means, they instead started from scratch and wrote a brand new parser.