14 years later, Hideo Kojima reveals why Peace Walker wasn't called Metal Gear Solid 5: "It faced strong opposition from overseas marketing"

Metal Gear Solid: Peace Walker.

Metal Gear Solid: Peace Walker launched on PSP 14 years ago, and for much of that time we've wondered why it wasn't made a proper numbered entry in the series. Now, director Hideo Kojima has revealed it's because of "overseas marketing."

"After creating MGS4, I strongly felt the need for a proprietary engine," Kojima says in a new tweet. "The leap forward for games in a vertical direction would only come after the engine was complete." That led to the creation of the Fox Engine that powered Metal Gear Solid V: The Phantom Pain. In the meantime, Kojima wanted to evolve the series "horizontally" - onto other platforms.