I see that some demos and games use music files from the Atari ST: .SNG (The Music Studio Song)

The built-in player is very simple, but plays a lot of files I've fed it (by file swapping).
I wonder why they didn't design it as a separate program to play this type of file?

Tutti Frutti - file TUTTY_2.PRG
NASA Guy demo 1 - built-in
NASA Guy demo 2 - ACC1.SNG
NASA Guy demo 8 - CALYPSO.SNG
NASA Guy demo 11 - TANGO.SNG

SNG songs I take here https://www.noniandjim.com/Jim/MusicStudio/MusicStudio.html