What is required for a plugin to work?

So.. I’m looking at some software called gallery (https://gallery.menalto.com/index.php) and I noticed it says it will operate as a plugin for phpnuke and another program (probably evil words to speak here, but bear with me).

I want to know if I can somehow use gallery as a plugin on wordpress? If so.. is it really just a matter of giving wordpress the primary index.php of gallery?