[canpan]

If I remember correctly, another game with a similar music system is Deus Ex from 2000. It is pretty approachable. If you own a copy, open any of the s3m music files in your favorite mod tracker editor. Each song file contains multiple versions of song sequences, depending on the mood (idle, battle, ...).

[all2]

I remember reading a PC Magazine article about Rogue Squadron for the N64. Apparently it was one of the first games to feature a context specific soundtrack.

[alabastervlog]

First one I remember it in was X-Wing (1993), five years before Rogue Squadron. Looks like Monkey Island 2 (1991) was the first to use the system. Dark Forces used it, too.