Donald Mustard ran a successful studio that showed what the Xbox and iPhone were capable of. Then, he became the face of one of the biggest and boldest storytelling experiments in history, to borrow a phrase, with Fortnite’s massive metaverse.

“I’m excited to spend time with my wife and family and am forever grateful for @TimSweeneyEpic and the Epic Games family,” he writes.

I will always remember Mustard best for Shadow Complex, one of the best Metroidvania games ever made, which helped prove out the market for digital-only titles when it arrived on the Xbox 360’s Xbox Live Arcade platform in 2009. It broke the platform’s sales records at the time, selling 200,000 copies in a week. His studio, Chair Entertainment, founded by members of the Advent Rising development team, also brought the award-winning Undertow to Xbox Live Arcade in 2007.

Mustard was both the creative and technical director on Shadow Complex, though many Epic Games employees are listed in the credits, too — Epic bought Chair in 2008, a year earlier.

By 2010, Mustard had switched from Xbox to the iPhone instead. Epic Games had just helped legitimatize iOS as a gaming platform with its then-incredible Epic Citadel tech demo. Mustard’s Chair turned it into Infinity Blade, a sword-swinging finger-flicking series that served as Apple’s go-to demo for the iPhone’s graphical chops for years afterward — despite originally being conceived as a Microsoft Kinect title you’d play with your arms. Nothing on iPhone looked anywhere near as good.

And then there was Fortnite. Originally a very different game, it was molded by PUBG’s success into the world’s foremost battle royale title and eventually became a game with a literal world-breaking narrative: cracks in the sky, giant kaiju battles, a black hole, not to mention reality-bending rifts that allowed Marvel, Stranger Things, Dragon Ball, Star Wars, Naruto, and Futurama characters to all coexist in the same universe. There’s nothing else like it.

In Friday’s goodbye note, he says that Fortnite’s teams are “in the best hands” and still working on “huge, jaw dropping, amazing things” to come.