Mount & Blade series, With Fire and Sword. This standalone expansion takes place in 17th century Eastern Europe, and is based on the novel of the same name by Henryk Sienkiewicz.
The game is an open sand box world in which you can choose one of three storylines, which determines your allies, your enemies, what provinces to conquer, what castles to siege and what quests to embark on. Firearms have been introduced to the battlefield has well as muskets and pistols, in addtion to hand-to-hand combat. The game also features multiplayer as well.
You can read the Strategy Informer preview, and a review will be posted shortly. The game can also be purchased digitally from Gamewatcher .