I've open-sourced all of this here: https://github.com/mogray5/debmod
so feel free to hack away at it and make it better.
The process of collecting mod changes and creating new packages once defined in the database is automated but there is the occasional manual intervention needed when the upstream mod devs take their mod source offline or move/merge projects.
Adding new mods/subgames to the database is a manual process at the moment and requires adding data to a back-end RDBMS database using SQL.
It's Debian centric (even the name) but if you end up making it work with RPM as well then feel free to create a pull request and I'll be happy to merge it in.