This includes any installments, whether it's the original, or the latest updated version.
I was mainly aiming for the one theme song that tends to make itself apparent in the soundtrack of all (or most) of a given series installments. Like Halo for example - the main theme was I think prevalent in at least 1-3 (at least, if not more), but IIRC it disappeared at some point.
*Kingdom Hearts - There are like 3 options I can think of as the "main theme." There's Hikari/Simple and Clean, Passion/Sanctuary, or Dearly Beloved. I personally think I'd choose Dearly Beloved, since it's what plays in the title screen of (I'm pretty sure) every single KH installment.
Not changing this sig until Pat Benatar is in Super Smash Bros. (Started 8/31/2010)
BRAVELY DEFAULT: 1075 - 0844 - 9134 + FS: Pumkaboo, Lampent, Dusclops.