This album is a "Music Library" (like all the APM albums), and this one was made by Tommy Tallarico.
So, i think the tracks are available for licensing (i am not sure how the rights will work with already used music like that Dirge Of The Spectres track though).
I am unsure that all the tracks from that albums were already used, so the majority of them might be "original works" by Tommy (until they were bought and used in a game)
EDIT:
official website
I think i was wrong abut this CD, "Endgame" is a series of Library but 2 albums called "Endgame Classics" (from Tommy Tallarico, and the other one by Richard Jacques) are probably compilation of videogame music.