Hideo Kojima has revealed one additional factor that made transferring PHYSINT from PlayStation to XBOX possible.

As we all know by now, Sony abruptly told Kojima it was cancelled, and after scrambling to find a publisher for three months, he settled on XBOX. But there was speculation that this would prove difficult now that he likely loses access to Guerrilla Games’ Decima engine.
As Kojima explained to IGN, they didn’t stop working on PHYSINT for that three months. In his words:
How I create the game is a little unique. The world, the game system, scenario, the visuals, the design, modeling, I’m still doing that. I’m still casting and also doing scans for the actors.
But the game system for the new technology, like enemy AI and stuff, I’m still experimenting on all of this. I have to change the story depending on how the game experiment works. So it’s not like we’re ready to go, or like it’s like a big team already.
Subsequently, Kojima hasn’t decided yet on what game engine PHYSINT will use either. It does seem if Kojima Productions were far in enough that they used Decima, its post-PlayStation revival may have been impossible.
