MOD files are a form of music files, but in a way it’s not. See it as digital music partitions with the instruments audio samples files attached to it. So when you playa mod file it’s not a recording that you are listening to but instead you are listening to your computer playing the partition with the instruments that where bundled with the file.
This file format originate from the 90’s, the composing software where called “tracker” it was used to create theses “modules” that could be played as is, but also could easily integrated in software such as games.
This cache as been on for a few year.
Be warned that it not small, being 32GB
The key is : BJA5BNZOVEAUNRKBBHEC2JPPNZRRAZCPU