YouTuber Omega52 upgraded Battlefield 3's soundtrack by replacing it with 8-bit audio from NES games. The sound effects are from Contra and Top Gun, and the background music is from Journey to Silius and Batman.

Unfortunately, this 8-bit soundtrack isn't available as an actual mod -- BF3 didn't ship with mod tools, and EA isn't likely to release any, despite strong fan support.

Hey, EA, bleep-bloop and take my money!

[reddit]