The Witcher III: Wild Hunt - Hearts of Stone is an add-on for The Witcher III: Wild Hunt. The story starts with a harmless contract: Finding and killing a monster in the Oxenfurt sewers. But soon everything goes wrong and Geralt is forced to to the bidding of a mysterious magician and solve a number of seemingly impossible tasks... The female lead is Shani, known from the novels and The Witcher.
This add-on is mainly set in the new area northwest of Novigrad (the Novigrad area excluding the city itself is about doubled) and the city of Oxenfurt. It continues the gameplay mix from the main game: exploring the landscape while doing some optional side quests and following the more linear and dialogue-heavy main quests. The only mechanical addition are enchantments which are used to add powerful effects to weapons and armor. However, they can only be applied to items with three runeslots. The craftsman first has to be unlocked with a substantial money investment and can also add runeslots to weapons and sells crafting recipes for runestones which are used for enchantments.