WAD: Back To Saturn X series
This is Back To Satun X's signature intermission music composed by James Paddock (Jimmy), Sarah Mancuso (esselfortium) and Xaser Acheron (Xaser), played through Gravis UltraSound emulation.

The GUS emulation was done through TiMidity++, with the use of this patches:
https://www.doomworld.com/idgames/mus...
Download Back To Saturn X E1: https://www.doomworld.com/idgames/?id...'>https://www.doomworld.com/idgames/?id...
Download Back To Saturn X E2: https://www.doomworld.com/idgames/?id...'>https://www.doomworld.com/idgames/?id...
If you're a Unity port user, the series is available through the official Addons.