It's actually going to be a mix of retro chiptunes with every other musical style under the sun. As in, each track has a chiptune element that is playing througout, often in the position of the melody driver, and then there are other instruments playing along with it. The end effect is pretty awesome and unique, not like something I've heard in any other game (well, actually the intro to Bionic Commando Rearmed did something kind of similar).
We'll be sharing the first of these coming up soon in a video!