Wolfenstein: New Order. It both has such a great spin on the [url=http://youtu.be/3y0jbna9zTE]60's sound[/url] or parody of existing songs. They told them couldn't turn The Beatles into Nazis, it wouldn't work. [url=http://youtu.be/69z_IN64EG4?list=PLjrBFx6ZKSKo2SKP-Fjo7Jjlua7YCL3aj]But then they did it anyways.[/url] And [url=https://www.youtube.com/watch?v=agBdkmz4nGA]the general ambient/background tracks[/url] are great too.

And before anyone dares forget, [url=http://youtu.be/mizSUxxuCiY?list=PLD61626F6813F6C5F]Jet Set/Grind Radio has a great OST.[/url]

Also, obligatory:
[youtube]6IjnoM5-mnw[/youtube]

[youtube]ULQgMntenO8[/youtube]

[youtube]oXRLoiD7G2k[/youtube]