Epic as in, "Amazing, could listen to that shit all day.":
Most boss music from the first Spyro the Dragon game, specifically Toasty and Blowhard. Twilight Bay and Wizard Peak are pretty awesome as well. Those are the results you get for hiring a proffessional. (The drummer from The Police did this music.)
Space funeral's soundtrack is also pretty ni- PLAY. THIS. FUCKING. GAME... http://gamejolt.com/games/rpg/space-funeral/3492/
Rayman: The Great Escape has cool music, specifically that jet-ski scene on the snake's scarf.
Twisted Metal and Saints Row IV: Who says you have to compose new music to sound awesome alongside your gameplay?
Epic Soundtracks, as in "Big and intense":
God of War, of course.
Dante's Inferno, which doesn't get enough credit. Fuck, NOTHING about Dante's Inferno gets enough credit, for example, the fact that it's actually a GOOD game based on the movie, and not a blatant money-grab, like most movie games. (No, I'm not a fucking retard that thinks the Divine Comedy was aactually a movie, the game actually based on a Western Anime-ish movie with one director per ring, which I'm pretty sure includes Guillermo Del Torro. (It would be a SIN not to let him work on a cartoon Dante dramatization in this day and age... See what I did there?) I'm sure that has good music too, but I've never seen it.)
Oblivion, Skyrim, pretty much every elder scrolls game.
Zelda: Twilight Princess
Brutal Doom. Fucking download that if you have any old Doom ROMs.