Art director Nate Wells worked at Irrational Games for 13 years, beginning in September 1999 and the company's System Shock 2 days. Yesterday we discovered Wells and a handful of other people working on BioShock Infinite were no longer with Irrational, and Wells' Twitter briefly teased a job change before being deleted. While the bulk of people leaving Irrational can be chalked up to industry turnover, Wells' departure stands out, for the public and Irrational Games founder Ken Levine.

"In a company of 200 people you're going to have turnover," Levine tells Kotaku. "We never like to see a guy like Nate leave because he's been here for a long time, but it's been 13 years and I think sometimes people want to spread their wings. I'm not going to stop people. We love Nate and I think we all remain friends. After 13 years he sort of finished his work on BioShock Infinite, as you will be able to tell when you see the game again... I think Nate's moving on to something else."

Replacing Wells is Scott Sinclair, the art director for the first BioShock. This rounds out the core BioShock team that has stuck with the franchise - which is an achievement all on its own, Levine says:

"As far as the team itself, the lead artist, the art director, the creative director, the lead effects artist, the senior sound guy, the lead programer and the lead AI programmer from BioShock 1 are all on BioShock Infinite. I don't think there's a single senior BioShock team member that isn't here, which I think is amazing and a testament to their commitment to the studio."