Halo 3: ODST. the track Rain is so epic and sad in an sense that evokes doom. it really brings out the mood of the game, and not a lot of game soundtracks do that quite as well as Martin O'donnel can. the classic halo theme makes the chief look like a badass, which is what martin and the rest of the crew want in the game. but in odst, you are at wits end, left to die, almost no chance of survival (but you make it out alive, so you're like the A-team) the entire city around you, once the greatest city on earth, is utterly destroyed, shrouded in mystery (audio files), enemies everywhere, and you are all alone, and Rain really brings that out in the game.
http://www.youtube.com/watch?v=F-Q04VwH8cs
also, from Halo: Reach, BRILLIANT. i haven't listened to everything that's been released, but this is the longest one which means it's probably the title screen song. martin like allusion between his music and the game, so here's the game; you're a fire and forget prototype solider who no one gives a damn about and you're on a military stronghold planet that is humanity's greatest symbol of security and comfort and in the end, it is completely destroyed with you on it. so the mood; eminent doom, just like the direction of the franchise. so far, it really makes me feel sad in a gloomy way and at the same time there is this epic doom approaching me FAST and it's slowly taking over. but then at the very end of the song, there is the uplift that makes me feel like there's still this last glimmer of hope left.
http://www.youtube.com/watch?v=Ocly_enQqJI&feature=related
these are two of the greatest peices of video game music i have ever heard, plus unforgotten also by martin o' donnel. if anyone tries to flame me and say "no, this here song from this anime game is the greatest!" then i will laugh in your face at the pure ameteur you display in your taste of music.