We'll see what Bungie comes up with.
Whether their first effort on the PS3 showcases their ability to optimize with the hardware, or repeat their success with the Halo franchise on even a smaller level remains to be seen.
I can potentially see them going back to Halo if the success isn't on the same level; it's natural to fall back on your greatest success.
Anyway, this isn't the first time the developer took a drastic change in platforms. As many are well aware, Bungie used to be one of the premiere game developers for the Mac OS before MS effectively bought them and the Halo franchise.







