In a blog post, Martin acknowledged that it has been a bit since he wrote the mythos and backstory for Elden Ring, and the man admits he loves worldbuilding. Having now seen the fruits of what the collaboration made, Martin seems quite pleased. "What they wanted from me was just a bit of worldbuilding: a deep, dark, resonant world to serve as a foundation for the game they planned to create. And as it happens, I love creating worlds and writing imaginary history," he wrote.
So, even though FromSoftware didn't think he would go for it, Martin bit their hook and went for it. "I did my bit, and handed off to my new friends in Japan, and they took it from there. And years passed. Videogames are as big as movies these days (bigger, actually)… and take just as long to create," Martin wrote, "But the day of ELDEN RING is finally at hand. And I've got to say, it looks incredible." (Emphasis Martin's, there.)
Good spot, Gamespot.