First off, if you're reading this, Carey - THANK YOU! I pulled a bunch of these tracks from your website a while back, and I've been putting bits and pieces together for a while, but these are fantastic.
Now, about the music for the rest of you.
Early_Ambient_CORE
Quite a slow and dark ambient track, with elements similar to one or two of the tracks from the FE shell. Sounds nicely foreboding, and conveys how you'd imagine a small force would feel landing on a strange, blue, and dangerous world.
Early_Ambient_MIRE
Follows mostly the same feel as the CORE track, with ambient sound effects (water, incests, animal roars) and jungle drums.
Early_Ambient_MIRE1
A much more percussive track than the other, this is clearly more an action track. Quite fast-paced, handy for a good fight.
Early_Ambient_REND
This one is available on Carey's website, and contains, again, echoes of the tracks from the FE shell. It also contains a fairly clear hint towards one of the Scion tracks that did make the final cut in the woodwind line. Similar feel to the others - a dark sound, captures a very different atmosphere than the final tracks used for Rend.
Early_bzcore1
Here, more melodic tracks begin to appear. This is quite dancey compared to the other music you will have heard so far, with a nice bass lick at the beginning and a more complex drum line. Synth leads, pads, a bell, dance drums, bass... and yet it still feels like it really could be Core.
Early_bzmire1
This track is quite creepy, and the intro reminds me of the FEAR soundtrack for those of you who have played it (reminds me of shearing metal). This is more percussive than the Core track, but still more melodic than the Ambient ones. I like the sound of the percussive chord pad especially. And again, echoes of the FE shell. the second half seems to cover the entire of FE's soundtrack

Early_bzpluto1a
This is more like the ambient tracks than the other two. It starts with percussion and some slight bass, builds with a chord pad, then drops back down to the feel of, perhaps, Ambient_MIRE1. It carries none of the feel the original Pluto maps had, but that's a good thing. It would probably work fairly well if the place didn't have the whole ghost-town thing going on.
INTRO
Simply the music from the intro cinematic. When Jayden, NK1 and I found this on Carey's website, we nearly threw a fit. It's utterly fantastic and was the best part of the game soundtrack I'd heard up to that point. You may think you get enough of a feel for the music in the cinematic, but listen to it here with the sound effects and voiceovers stripped away completely and it will seem completely different. It's a beautiful piece of music. (Ignore the little click at the beginning, it's probably a DAW metronome - a better copy can be found on his website on the /mp3 page). If you can, when listening to this, turn the bass up a little.
isdf_2
In-game. Fan-titled as Barrack Waltz (Track 2 on your CDs, people).
isdf_3
In-game. Scion Encounter. Track 3.
isdf_4
Not heard this one before, and I like it. Fits with the other tracks, but has a slightly greater emphasis on the strings. Quite soft, slow and mournful. Feels very much like a character death moment. A beautiful chord sequence, and the woodwind sits very nicely on top. Also has a lovely piano line, which isn't something that appears in any of the released tracks (but does appear in quite a few of the unreleased ones). As with many of these tracks, I think includes musical references to the other tracks - small sections of tune and rhythm carried across from one track to another. I'm sure I caught one, but I can't be entirely sure.
isdf_5
I have a copy of this from the website. Ties the rest of the soundtrack in with the shell music (listen for the triangle - can't miss it). Quite sedate at the beginning, but warms up a little a short way through with the brass and strings coming in. Has a very nice chord sequence that I caught myself humming at one point (sad, aren't I?). Drops back nicely to the bare rhythm at one point. Feels like a drive around an alien jungle, to be honest with you.
isdf_6
Track 5 - Drive the Rush
isdf_7
Track 4 - Weather the Storm
isdf_outro
The fanboy in me screams out in joy. This is the track from the ISDF ending cinematic and thus has all the epicness you would expect. Listen to it on its own, without sound effects and voiceovers, and it is fantastic. Enough to make my spine tingle - which only happens with *exceptionally* good music. Epic brass (wow!), clearly recapitulates one of the intro's main themes, takes its own sinister turn, then follows it up with the triumphant brass line. Nice use of a choir as well.
scion_1
Track 6 - Through Marsh and Mire
scion_2
Track 7 - Body Hammer
scion_3
Track 8 - Strike at Core
scion_4
Not heard this before either. Much gentler than the other Scion tracks so far, and the intro percussion feels almost like it could have been one of Sonic Mayhem's Borderlands tracks (and that's a very good thing). Continues some of the themes in other tracks, expands on them nicely. The choir is used again (at least part of it), and the strings are very good indeed. Brass line clearly brings back one of the main themes, pinned by some very good unresolved string sequences. The brass really tries to resolve the line but it never really gets there, which sounds absolutely amazing.
scion_5
Track 9 - Stalking a Sentry
scion_6
This track is also on Carey's website. It's a little less organic than the others (mostly because of the synth part, which I like). Links in with the themes of some of the earlier Scion tracks very nicely, and even with some of the ISDF ones - just little enough to avoid sounding like a plain copy. It also includes something different - the plucked strings make this sound a lot like the Call to Power 2 soundtrack. Again, the line never really resolves, which is lovely.
scion_outro
Almost had another screaming fanboy moment. Rather than going all-in at the beginning, this track instead builds up the epic triumphant...ness slowly, bringing in strings, brass, choir, harp(!), etc. and then pulling the main theme in and resolving it. A beautiful track, much gentler than its ISDF equivalent (of course), and a fitting end to the (good side of the) game.
I'm Cutting my first post short here as It's late and I want some food. The next post will deal with the final twelve tracks, which are the unused_ ones and the wormhole track.