I have very fond memories of Crackdown, one of the earliest Xbox 360 exclusives and a game that, in many ways, still stands strong today. I'd love to say those memories are thanks to the collecting of orbs, of jumping over buildings and driving stupidly large trucks, but they're not. They're thanks to a single song, played at the game's opening menu screen.

Crazy, right? Menu music. Whatever. But what Scottish developers Realtime did when selecting the track to play at Crackdown's opening was a stroke of genius.

Rather than composing their own theme, they licensed a track by Japanese artist DJ Krush. Now, it helps here that I'm a big fan. I've seen the guy live and own a ton of his records. But in the track they chose, the instrumental version of Paradise Bird Theme, they picked what I think was one of the most perfect game songs of all time.

Why? Because it is the polar opposite of Rihanna x Battlefield 4. It is absolutely perfect for the game, and the world the game is presenting, as though Pacific City's skyscrapers popped into the recording studio and wrote a ballad. This helps get your understanding and immersion in the game world off to the best possible start before you've even started.

It's more important than simply enjoying a song, though. I literally cannot separate this track from the game, and I can't think of the game without the track. Even when listening to the album it appears on, 2001's Zen, I get flashes of Crackdown, and can hear the gruff Agency announcer's voice in my ear.

It seems reckless, maybe even a little rude to be saying a song - one that wasn't even written with the game in mind - can so define an interactive experience for me, when so many developers spent so many years toiling away on programming, animation and design.

But hey, that's what's happened.

Other songs have done similar things - Magnus Birgersson's work on Mirror's Edge, for example - but for me none have been as inseparable as Krush and Crackdown's team-up.

What about you guys? Ever hear a song in a game that becomes such an important part of the game itself that you can't split the two?