The Witcher 3: Wild Hunt - Hearts of Stone is now available on GOG.com and Steam, offering the first expansion for CD Projekt RED's RPG sequel. There was also to be the release of a physical disk for this (apparently though outlets called "stores"), but this forum post has word that this is delayed in North America (thanks The Escapist). Word is: "However, it has come to our attention that, due to logistical problems, customers will be unable to obtain the physical edition of the game for several days after launch. We are working with GameStop to fix this situation as soon as possible and deeply apologize for the inconvenience." Here's the deal on the add-on:

Professional monster slayer is hired to deal with a ruthless bandit captain who possesses the power of immortality.

Step again into the shoes of Geralt of Rivia, a professional monster slayer, this time hired to defeat a ruthless bandit captain, Olgierd von Everec, a man who possesses the power of immortality. This expansion to “The Witcher 3: Wild Hunt” packs over 10 hours of new adventures, introducing new characters, powerful monsters, unique romance and a brand new storyline shaped by your choices.