Strategy Informer  

Valve has confirmed that Portal 2 has sold 4 million copies worldwide since its launch in April 2011.

No statistics have been given regarding sales on individual formats. The original Portal also sold over 4 million copies, with Valve indicating that the PC version outshone the sales performance of its console brothers.

Valved has also today released the Puzzle Maker for Portal 2, as part of the free Perpetual Testing Initiative DLC.

Related games: Portal 2 (PC), Portal 2 (PS3), Portal 2 (Xbox360)