The company behind Bioshock and Bioshock: Infinite -- two of the most critically acclaimed games in a generation -- is abruptly closing up shop. Ken Levine, the creative force behind Irrational Games, announced on the company's website on Tuesday that he and a small team from the company are moving on to new projects.

"We built Rapture and Columbia, the Von Braun and The Rickenbacker, the Freedom Fortress and some of the nastiest basements a SWAT team ever set foot into," reminisced Levine in his message. "We created Booker and Elizabeth, the Big Daddy and the Little Sister, MidWives and ManBot. In that time, Irrational has grown larger and more successful than we could have conceived when we began our three-person studio in a living room in Cambridge, MA. It's been the defining project of my professional life."

But now Levine is leaving Irrational Games behind and moving to a new smaller developer within Irrational's parent company Take-Two Interactive. "I am winding down Irrational Games as you know it. I'll be starting a smaller, more entrepreneurial endeavor at Take-Two," announced Levine, who stressed in the message how he would take care of the Irrational team members who didn't make the cut. "That is going to mean parting ways with all but about fifteen members of the Irrational team. There's no great way to lay people off, and our first concern is to make sure that the people who are leaving have as much support as we can give them during this transition."

Laid off employees will have opportunities to be hired within other studios in Take-Two Interactive, and Levine's company is will host a third-party recruiting day, along with financial support for employees.

Gamers don't need to worry about losing the last Bioshock installment -- the second half of the Buried at Sea downloadable content (DLC) for Bioshock Infinite is still slated to be released digitally on March 25.

As for Levine -- largely considered the driving force behind the innovative, genre-melding titles released by Irrational Games -- the game maker offered few clues about his next ventures. "In time we will announce a new endeavor with a new goal: To make narrative-driven games for the core gamer that are highly replayable," wrote Levine. "To foster the most direct relationship with our fans possible, we will focus exclusively on content delivered digitally."

Levine wrote that he considered leaving Take-Two and creating a new startup, saying, "Initially, I thought the only way to build this venture was with a classical startup model, a risk I was prepared to take." But Take-Two convinced Levine that he could "pursue this new chapter" within their walls, with their support.

The Bioshock series, which according to Levine has generated over half a billion dollars in its time, may not disappear entirely in the future: Levine wrote that he's handing the series over to 2K, another subsidiary of Take-Two Interactive, though without Levine, a new sequel in that universe would be Bioshock in name only (like Bioshock 2).

But it will be interesting to see what comes out of Levine's new project. As he wrote of his new startup, "If we're lucky, we'll build something half as memorable as Bioshock." If we're all lucky, you will, Ken.