Koji Igarashi has left Konami after 20 years and Castlevania and Metroidvania and he's leaving because Konami's direction is away from the hardcore.
Speaking in an interview at GDC, he states that, "My style of creation, the sort of game experiences I'm really good at don't fit that trend (for the casual market)..."
He told Polygon that, "Unfortunately, I'm good at making core experiences, so it was two years of making a game that leaned too 'hardcore' for the social market. So it was canceled. Then I'd try again and be canceled. And again and be canceled.
"That happened several times, more because my natural style is more akin to a hardcore game."
In terms of his future, he's setting up his own studio and "he hasn't ruled out collaborating with some of his former colleagues and co-creators, like artist Ayami Kojima and musician Michiru Yamane.
"Kojima-san and Michiru-san are both amazing creators and it's fantastic to work with them," he said. "I'd love to work with them all the time, if I could. That's definitely something I am thinking about, but naturally there's lots of talent I've worked with in the past and I'm planning to see if we could collaborate in the future."