Let's not forget our main man Jesper Kyd.
Freedom Fighters is about an american average Joe named Chris who gets forced into fighting the invading Russian army occupying Brooklyn. Kind of like Red Dawn with more explosions and gunfights. Russian chanting and propaganda theme everywhere. Even if you haven't played the game, I'd wager you've probably heard the music before.
State of Decay is when the Zombie Invasion hits Hodunk Podunk Pennsyltuckey in the middle of nowhere and a bunch of locals with hunting rifles and shovels need to band together and fight to survive. Lots of rural camping-esque theme to the musical scores.
I love video game OST simply because it's meant to be repetitive and in the background, and that's all I want out of music.
Freedom Fighters OST I've had on my machine for years, I can't remember where I got it, though it's definitely online still.
State of Decay though I actually managed to rip the music from the game's files. Ya can still buy them on Amazon or iTunes.