Hideo Kojima, who partnered with Sony on his upcoming game Death Stranding partly due to their relationship, said at Develop Brighton earlier today (through a translator) that the PlayStation is to thank for Metal Gear Solid.
When Mark Cerny brought up the rapid console hardware advancement between Metal Gear 2 in 1990 and Metal Gear Solid in 1998 (skip to 7:20), and how it changed what he was able to create, Kojima replied, “I made Metal Gear 1 and 2, and at that point the series, for me, was complete and it was finished, and I started working on other adventure games.”
Mentioning that Metal Gear was always meant to be a hide and seek game, and the original idea was to have players hiding and the viewpoint would change as a result, Kojima added, “However, back then we didn?t have any 3D polygons, we had to do everything in 2D. So for Metal Gear I had no choice but to use game design where you look from up above.” When working on those other adventure games after Metal Gear 2, Kojima learned that a new piece of hardware called PlayStation was going to be released, and it would allow for real-time polygons. Because of this, Kojima says he was able to fulfill his original vision:

For me, Metal Gear was a series that was complete and finished to me, but at that point I thought I would be able to make what I originally intended to do with this technology of being able to polygons in real-time. So, you can say in a way that thanks to PlayStation Metal ...