Portal 2 is a sequel of a 2007 puzzle-platform game developed and published by Valve - Portal, which was released in 2011, adding several new gameplay mechanics and a cooperative multiplayer mode.
Valve's original Portal was noteworthy for its witty and acerbic dialogue, creativity in blending the previously incompatible brain-teasing-puzzle-game and first-person-shooter genres, and relative shortness. With Portal 2, Valve has left intact the first quality, expanded and elaborated on the second, and done a bit to address the third. What this adds up to is a sequel that stands up proudly to the original, updating the characteristics that made it a distinctive success without dulling their memory. Limited multiplayer and post-campaign options slightly diminish the replay factor, but in almost every way Portal 2 is just as amusing and exhilarating as its predecessor.