As you probably already know, developer Platinum Games is producing a very different game from what Kojima Productions originally envisioned.
Metal Gear Rising: Revengeance will be a slam-bang action extravaganza, which is what Platinum does so well ( Bayonetta , Vanquish ). When it first began its life with Kojima's team, there was unsurprisingly more stealth involved and the interesting part is that Rising was playable at one point.
And at that time, there were certain levels and bosses in place that just didn't fit with Platinums' new vision. In speaking to OPM UK , Kojima Productions producer Yoji Korekado and Platinum games director Keiji Saito spoke about the significant changes. Said Korekado:
"The script was finished and the boss concepts were finished. The design was finished with those levels, and the levels were at the point where we could play it through in a white box – but we couldn’t come up with a core concept to tie it all together. In the end, we couldn’t finish the game.
Just to brag a little bit about our designs, we believe that the bosses we created for Metal Gear Solid: Rising were probably some of the best in the series, but Saito came in and said, 'We’re not going to use these bosses.' So you’ll not be seeing them this time around. "
The bottom line is that those boss fights just didn't fit the new style and mechanics. Saito implied that the original boss encounters were more like traditional MGS fare, as they often required "stealth and cunning." But that just doesn't gel with a straight-up action game, now does it? Oh, don't get all bent out of shape; Metal Gear Rising: Ground Zeroes is on the way and remember, Revengeance is just a spin-off.
Related Game(s): Metal Gear Rising: Revengeance