jorlin: I see that Gog converted all in-game music into .ogg files,
My guess is that Gog uses a helper program to hook all the ingame music calls to that helper program that plays the ogg files. An .exe is no batch file, so I don't really know what the Gog customizations do, or I'd make a symbolic link to a similar linux program.

carlosjuero: It was freeware for a short while as a promotion for Betrayal in Antara. In 1997 the game was released for free (the Floppy version) to hype up the new game, the rights owner has since 'revoked' that particular license and the game is no longer 'legally' free to obtain.

There was no press release or anything stating this though, they just removed the download from the Sierra website at a certain point and it was assumed that people would know, at that point, that the game was no longer free - though it hit the Abandonware scene in the early 2003/4 period.