A pack of music ripped from a MS-DOS game called "Alien Trilogy".
Simply extrac to ns\music(you can increase the likelyhood of these music files being played by moving out the default NS music files). Example of extraction path: C:\Program Files\Valve\Steam\SteamApps\accountname@example.com\half-life\ns\music


Credits: Acclaim, Probe Entertainment, and Sculptured Software.