I remember places like Zeuxworld would try to archive everything (even before DigitalMZX came around) and was impressed with the size of their library. But then I'd stumble on personal websites on places like Geocities or Angelfire where people would post their ZZT and MegaZeux worlds. The worlds on these personal sites weren't in any of the archives. I wouldn't be surprised if there were still a handful of these on the web alone. Who knows how many old hard drives out there still hold rare games and engines