The framing story is set in the 21st century and follows Desmond Miles as he relives the genetic memories of his ancestor, Ezio Auditore da Firenze, to uncover the mysteries left behind by an ancient race known as the First Civilization in the hope of ending the Assassin-Templar conflict.

The main narrative takes place at the height of the Renaissance in Italy from 1476 to 1499, and follows Ezio's journey as an Assassin while seeking revenge against those responsible for the death of his father and brothers.

During development, two chapters—titled The Battle of Forlì and Bonfire of the Vanities—were cut from the game due to time constraints, but were eventually released as downloadable expansion packs on Xbox Live and later to other platforms.

Assassin's Creed II is an action-adventure game played from a third-person perspective and set in an open world based on late 15th-century Renaissance Italy.

The Animus 2.0, a new version of the machine of the same name present in Assassin's Creed, provides in-game context for changes and additions to several game elements.

[2] Each of the places the player can visit is more detailed compared to Assassin's Creed, and NPCs have a more human-like behavior; for example, civilians can sometimes be caught coughing or sneezing.

In addition, players are able to purchase artwork for their villa, obtain new armor as the game progresses, and even dye Ezio's clothing with a number of different colors.

The surrounding property, which includes vendors selling items such as medicine, weapons, and clothing dyes, can be upgraded with earned florins, granting Ezio discounts at the shops and increasing the passive income that is generated by the villa over time.

Cities also contain hidden locations such as catacombs and caves (the design of which have been compared by the developers to the Prince of Persia series), where the objective is to navigate the area.

[5] After the events of the first game, Desmond Miles (Nolan North) is rescued from Abstergo by undercover Assassin Lucy Stillman (Kristen Bell) and taken to a safehouse, where he meets her team, consisting of historian and analyst Shaun Hastings (Danny Wallace) and technician Rebecca Crane (Eliza Schneider).

They have constructed their own Animus, which they intend to use to train Desmond as an Assassin through the "bleeding effect," which allows the user to learn their ancestor's skills at a rapid pace.

Desmond is instructed to relive the memories of Ezio Auditore da Firenze (Roger Craig Smith), born into a wealthy Florentine family in 1459, during the Italian Renaissance.

His journey spans over a decade and leads Ezio to make several allies, including inventor Leonardo da Vinci (Carlos Ferro), who provides him with equipment based on information left by the Assassin Altaïr Ibn-LaʼAhad; statesman Lorenzo de' Medici (Alex Ivanovici), whom he saves from the Pazzi's assassination plot; and Caterina Sforza (Cristina Rosato), the Countess of Forlì.

Eventually, Ezio uncovers the identity of the Templar Grand Master, Rodrigo Borgia (Manuel Tadros), who plotted to secure control of Italy and obtain a powerful Apple of Eden.

Inside the Animus, he finds glyphs similar to the drawings he found in his cell at Abstergo, which, when deciphered, reveal a video file of two human slaves stealing an Apple.

As they head to a new location, Lucy informs Desmond that the Assassins have detected strange occurrences in the Earth's magnetic field; a solar flare is scheduled to occur in a few months, which will likely trigger the same event that ended the First Civilization.

In 1488, shortly after recovering the Apple of Eden from Rodrigo, Ezio meets with Mario, Leonardo, and the Assassin Niccolò Machiavelli (Shawn Baichoo) to discuss what to do in order to protect the artifact, ultimately deciding to send it to Caterina Sforza in Forlì.

However, when Ezio and Machiavelli arrive in the city, they find it under siege by an army of mercenaries led by Checco and Ludovico Orsi, who have been hired by Rodrigo to obtain a map made by Caterina's late husband showing the locations of Altaïr's Codex pages, which in turn lead to the Vault.

Suspecting that the thief is a friar, he travels to a nearby monastery and questions the local abbot, who reveals that the man who stole the Apple is Girolamo Savonarola.

[8] A promotional video was released by Ubisoft on April 6 showing a skull, some hidden blade designs, and Leonardo da Vinci's flying machine on a scroll.

It was also revealed that the humorist Danny Wallace would be voicing a new character in Assassin's Creed II: Shaun Hastings, a sarcastic historian assisting Desmond.

[20] On October 20, 2009, Ubisoft announced a series of short films, to be broadcast via YouTube, that would provide additional back story and the introduction of some of the characters found in the game.

The shorts, collectively called Assassin's Creed: Lineage, came in three parts and were developed by Ubisoft's Hybride Technologies, who previously worked on the films 300 and Sin City.

Included also are three bonus areas and missions, an art book, a DVD with part of the game's soundtrack, one premium PS3/Xbox 360 theme, behind the scenes videos, and 2 desktop wallpapers.

[35] On December 1, 2009, Ubisoft announced The Battle of Forlì, the first of several downloadable content (DLC) expansions for the PlayStation 3 and Xbox 360 versions of Assassin's Creed II.

It was followed by Bonfire of the Vanities on February 18, 2010, which sees Ezio returning to Florence to deal with Girolamo Savonarola during the mass burning of sinful objects in the city.

The available awards are an Assassin's Creed II theme or wallpaper for PC and PlayStation 3, five additional throwing knives, Altaïr's outfit and the Uplay exclusive Auditore Family Crypt map.

This costume dye is unlocked by entering a code obtained after buying the Assassin's Creed II 3D mobile game from the Verizon App Store.

[63] The Windows version of the game uses Ubisoft's Uplay platform, which includes a digital rights management (DRM) system that initially required all users to remain connected to the Internet while playing.

[76] Ubisoft's Philippe Bergeron stated that potential settings could include England in the Middle Ages, during the era of King Arthur, and feudal Japan, the latter of which had been a "personal favorite" of many in the staff.