BioShock Infinite has sold over 4 million units, according to publisher Take-Two Interactive.

Take-Two's chairman and CEO Strauss Zelnick noted during a financial call today that "BioShock Infinite is North America's best-selling multiplatform release so far this year, according to NPD. The title's crossed the 4 million unit selling mark and we expect it to become the top-selling release in the BioShock franchise."

BioShock Infinite has dominated the game industry today with news of its three just announced DLC packs: the combat-driven stopgap Clash in the Clouds, and the underwater steampunk noir Burial at Sea, a two-part adventure that take us back to the series' starting point Rapture.

Tom Bramwell already reviewed Clash in the Clouds, which he found pleasant, but ultimately forgettable, while he also interviewed creative director Ken Levine about the far more intriguing Burial at Sea.