Pitch-black is a module file tune by Milan Kolarovic (aka Acumen). Mod tunes were popular in the late 80s and 90s, both in the demoscene and as music for computer-games (Unreal, Deus Ex, and Age of Empires all used module music).
There were a couple of reasons for this. The quality of sound the mod files could carry for their small file-size facilitated sharing over turtle-slow early internet: this song is 3.00mb as an mp3, but as a fully uncompressed .it file it is 1.52mb (and the mp3 format wasn’t published until 1993). The module format meant you could create electronic music on your Amiga as easily as editing a spreadsheet, through programs called trackers. And, unlike MIDI, a mod tune carries all of its component sounds with it, so that it is portable to any computer without change in sound.
A great source for mod tunes is the Mod Archive. Winamp is all you need to play most mod files.