Even remastering/mixing, the IP would still be in the hands of the composer(s) ; Looks like composer was Russell Shaw and the music/sound programmer was Tony Cox.
That aside, the rights do seem to still be in the hands of EA. Thus derivatives, remixes, remasters or whatever you want to flag it as, would be a no go (classed as a derivative work
. Copyright can only be issued for a derivative work "only if the derivative work is lawful, because of a license or other "authorization.""
Although from a performers perspective, PRS
has the same stance about arrangements of tunes that are within copyright. "You must check with the copyright owner of the original copyright material that they grant their permission for the arrangement"
This type of remix/master/whatever would be classified as a "purely adaptive arrangement"; not altering the primary or secondary melodies, keeping the chord progression etc..
You could potentially use snippets under the guise of samples, but it still needs to be a "new" composition.
I think there would be less of an issue if the originals (or remixes) were released as a mod pack or similar (not included with the game) released by an individual.
Bottom line, I don't see the original tracks being able to be released with the game without permission from the copyright or IP holder.