I was reading this thread from top to bottom today, and the "layered" audio concept sounds good. But if I may, the first thing I thought of when I began reading this thread: Has anyone here played Dungeon Keeper 2?
DK2 had perhaps the best music system I've ever seen in a game. It could ratchet the music up to epic proportions, bring it up and down based on the intensity of combat, etc., but as a player, I almost
never actually noticed. It was combat mood music at its best: Perfect style, yet completely unobtrusive. (I seem to recall the most powerful music was only pulled out when the player called down a giant uncontrollable demon that would wade into the battle, destroying anything and everything until the timer ran out.)
Later, when I used an XMMS plugin to extract the music, it was split into four tracks or so for each tune. But playing each tune, I found it was interspersed with clicks every few bars. It finally dawned on me: They weren't just changing tracks when combat came around, they were switching from one to another in mid-tune, a sort of "segmented music". Those clicks were possible transition points, and each subsequent track added a few extra instruments, increased the emphasis somewhere, etc.
That means it wouldn't
change tunes, i.e. start at the beginning of a track; rather, it might play the intro of the level 1 tune for a bit, then a few bars from the level 2, then back to the middle of the level 1 tune, then maybe 2, 3, even 4, then slowly taper back off, backing out into 3, 2, 1, and eventually finishing the tune with a proper exit. The proposed layered system is similar, but from what I understand, they're talking about songs that can transition into each other; I'm referring to songs that essentially
are each other, except with different levels of intensity, ready to be called upon in mid-tune.
As I recall, the base-level songs were probably designed to be played relatively end-to-end -- extremely ambient, designed not to bother the player at all, but ready to increase. (Actually, I think the lowest level was just silence, plus various ambient dungeon noises.) But once it gets into the higher modes, I doubt it would actually exit the song; it probably loops (seamlessly) until the battle's over, though I haven't played it for a while.
Anyway, just tossing out the "segmented" idea. It may be too difficult to pull off, given the styles of music we're after and the tools available, but it's still one of the best music systems I've ever played under.
On a different note, after getting tired of the same music over and over, I went through the entire collection of songs by the Precursors, a music mixing project for the Ur-Quan Masters (UQM), the excellent fan-based continuation of Star Control 2 once the source code was opened. I added every song to the most appropriate music category playlist, and I've found they work great.
Maybe it's just a question of different tastes, or maybe I'm just too big a Star Control 2 fan for my own good, but I found (for example) their 10-minute "outer space" music to be great for setting the mood in space flight, and their "starbase" main menu song great for visiting bases. I don't know what the license terms on their tracks are, or whether anyone would be interested in using them, but I'm just suggesting more what I consider "space music" -- less of the perky synth music, more of the low ambient, almost eerie music. But again, that's just my taste...
I'll say one thing more, though: I
definitely had enough of the "alienrockelectro" track, since I had several factions assaulting me at every jump point.
Not a bad track, just, I was hearing it
all the time and it was starting to grate on me.
Finally, I think it's been mentioned now and then, but I think Half-Life is the perfect example of how using silence a lot can dramatically enhance the value of the music when that time comes. I'm not saying space should be a silent, oppressive place -- believe me, I was eagar to get my music working after playing in silence for a while. But I'm just tossing in my vote for occasional breaks of silence, preferably going straight into combat music (or back into space music if the silence becomes too long).