The Witcher 2 is a single-player fantasy role-playing game by CD Projekt RED, starring Geralt, the hero from the first game released in 2007. Geralt is a witcher, a ghost-haired mutant that can wield swords and magical powers to dispatch foes. Expect a large cast of characters to interact with, plenty of ways to upgrade and customize Geralt to suit your play style, and at least one boss fight against a giant tentacle beast.
From what's been said about the game so far, The Witcher 2 is enormous. The official word is 40 hours long, though it's unclear how much that may vary if you decide to take part in all the side quests and minigames. Like in the first game, your actions while playing affect what happens later. In the sequel, this may mean you'll miss entire towns (as well as the associated storylines and side quests) on your first playthrough. According to the game's official site there'll be four different beginnings and 16 possible endings. CD Projekt RED is using an entirely new engine for the sequel, which basically means The Witcher 2 looks significantly prettier than the original, which utilized a modified version of BioWare's Aurora Engine.
Combat has also received a significant overhaul. Gone is the restrictive timing-based system used in the original, replaced by a more free-form system that should be more familiar to those who play third-person action games. You'll be able to equip lots of different armor pieces this time, as well use weapons, spells and alchemical components to kill your enemies. - IGN
Full review in progress:http://pc.ign.com/articles/116/1168535p1.html