BioShock 2 and the upcoming The Bureau: XCOM Declassified.
His departure is due to a change in his philosophy. "I thought that AAA was all I'd ever want to make, in the sense of production values," Thomas stated. "I was such a fidelity whore for so long that I would refuse to engage with the meaning of more primitive-looking constructs, and I think that was my weakness. But quite the opposite is happening lately. The projects made by two or three auteurs, or sometimes just one, are the ones that are speaking to me and taking me out of my comfort zone. I feel like out of my comfort zone is where I'm forced to stay learning, to retain that student mind. And I think I was at my worst when I thought I knew it all, if that makes any sense."
He went on to say that BioShock never "spoke" to him. "It cemented for me that while BioShock spoke to me, it'll never be for me what it is for Ken," he mused, "I've expanded that legacy here and there, but I could never have created it from scratch. I need to build something that is, to me, what BioShock is to Ken. No matter how long it takes, I have to start now."
When he helped Irrational finish BioShock Infinite, however, he found attached to the concept of ambiguity in storytelling, especially that particular game's ending.
"Without spoiling things for anybody, there are elements of the ending that spoke to me," realized Thomas. "And I wanted to make something that evoked those feelings more consistently throughout. And that could be a niche within a niche. I have yet to complete that experiment, but it's something that's really driving me right now."
Thomas plans to develop a game that is immersive like Thief and BioShock, but "with a radically different focus."