Once upon a time, before Github in the days when a "lightbox" was innovative new CSS technology, there was a young student of computer science. He had a bunch of .jpg files from a trip and he had a cheap PHP-centric web hosting solution called Dreamhost. He thought it would be nice to put the photos online, but did not want to deal with fancy gallery software that would require a MySQL database and a laborious import and captioning process. He just wanted a single PHP file he could drop in the same directory as the images.
Unfortunately, most of the extant software which did that was absolutely terrible. So he wrote this gallery, which is not absolutely terrible, and it at least makes use of basic HTTP features like Expires: headers (not common in cheap PHP scripts!)
The young student shared his design with a small group on IRC, for advice and feedback.One person from that group thought the gallery software was very cool, and shared it with others. Before too long, it made the top of the programming section of Digg. This was, of course, before the student felt the software was truly ready. The next thing you know, people in southeast Asia who didn't know what they were doing were not just installing the software, but also copying the student's Google Analytics identifier tag from the demo gallery for no good reason whatsoever.
Truly, these were exciting times.
Later, the student actually found himself employed and writing software for money. He wrote much better software, and found that he enjoyed other programming languages more than PHP.
It's 2016. I live on a different continent. Moo.js is no longer the state of the art. PHP has advanced two major versions and has features like namespaces.
This code is being preserved as open source on GitHub for posterity in case someone wants it in the future (if only for the historical record of these dark days). Some day I might actually return to the problem of easy-to-use gallery software, approaching it with modern PHP and modern JavaScript and modern CSS.
Don't hold your breath.
Don't expect support for this old software.