Or possibly the other way round? 0hh1.com was registered in 2014 according to whois info, the puzzles on this site go back to 2011. (I'm not claiming this is proof, of course)
They're older than that, this kind of puzzle is called a Takuzu or Binairo and was invented in 2009 by a pair of Belgians: https://fr.wikipedia.org/wiki/Takuzu
kmm|8 years ago
rplnt|8 years ago
I think this is a nice case of taking something interesting and making it more approachable, perhaps even fun.