The Witcher 2: Assassins of Kings (Polish: Wied?min 2: Zab?jcy Kr?l?w) is an action role-playing hack and slash video game developed by Polish studio CD Projekt RED for Microsoft Windows, Xbox 360 and OS X. It is a sequel to the 2007 video game The Witcher, and was released internationally on May 17, 2011 for Microsoft Windows, and on April 17, 2012 for Xbox 360. Like its predecessor, the game is based on the book series of the same name by Polish author Andrzej Sapkowski. The game has been a critical and commercial success selling more than 1.7 million units for the PC and Xbox 360 as of May 2012.[7]