The Assasin’s Creed is a video game series which features the protagonist, Desmond, as a descendant of a long line of Assassins who fled his nomadic family in search of a normal life. Desmond is a modern day bartender who is kidnapped by the mega corporation Abstergo Industries of the Knights Templar. They force Desmond to use the Animus to experience his ancestral memories in hopes that he will lead them to the Pieces of Eden that hold great power. Desmond is rescued by a group of modern day assassins and they are on a mission to find the powerful artifacts first in order to save mankind.

As Desmond experiences the memories of his ancestors, he begins to absorb their skill and gifts as well such as the Bleeding Effect. Some of Desmond’s memories go back to the Crusades, 15th Century Italy, 16th centuries of the Renaissance and following the story line to seek out the Piece of Eden known as The apple and The Staff. To top it off Desmond learns of prophetic wars that will end the world in 2012 and has visions about the First Civilization.

Though the game is presented through the protagonist Desmond Miles, the bulk of the game is played as Desmond experiences the memories of either Altaïr or Ezio through the Animus. This provides a means of a diegetic interface for the player, showing Altaïr or Ezio's health, equipment, goals, and other features as part of the Animus interface. The Animus is based on the player, as Desmond, controlling the assassin to maintain the synchronization between Desmond and his ancestor's memories. Performing actions that go against the Assassin's way or dying breaks the synchronization, effectively requiring the player to restart at a previous checkpoint. Furthermore, the player cannot explore outside of areas that the assassin has not experienced yet. There are also abnormalities within the Animus from previous users of the device that the player can find, linking to the larger story.

While playing as the Assassin characters, the games are generally presented as third-person in an open world, focusing on stealth and parkour. The games use a mission structure to follow the main story, generally assigning the player to complete an assassination of public figureheads or a covert mission. Alternatively, several side missions are available, such as mapping out the expansive cities from a high perch followed by performing a "leap of faith" into a haystack below, collecting treasures hidden across the cities, exploring ruins for relics, building a brotherhood of assassins to perform other tasks, or funding the rebuilding of a city through purchasing and upgrading of shops and other features. At times, the player is in direct control of Desmond, who by nature of the Animus use has learned Assassin techniques through the bleeding effect, as well as their genetic ability of Eagle Vision, which separates friend, foe and assassination targets by illuminating people in different colors. Through the Animus interface, the player can go back to retry any past mission already completed; for example, in Assassin's Creed: Brotherhood, the player achieves better synchronization results by performing the mission in a specific manner such as by only killing the mission's target.

The games use the concept of "active" versus "passive" moves, with "active" moves, such as running, climbing the sides of buildings, or jumping between rooftops, more likely to alert the attention of nearby guards. When the guards become alerted, the player must either fight them or break their line of sight and locate a hiding place, such as a haystack or a well, and wait until the guards' alert is reduced. The combat system allows for a number of unique weapons, armor, and moves, including the use of a hidden blade set in a band on the Assassin's arm, and which also can be used to quietly assassinate targets.

The game has evolved into other versions such as Assassin’s Creed II, Assassin’s Creed: Brotherhood, Assassin’s Creed Revelations, Assassin’s Creed: Altair’s Chronicles, Assassin’s Creed: Bloodiness, Assassin’s Creed II: discovery, Assassin’s Creed: Project Legacy, Assassin’s Creed: Lost Legacy, and Assassin’s Creed: Miltiplayer Rearmed. Ubisoft has expanded Assassin’s Creed franchise to other media including films, comic books, and novels. Some examples include: Assassin's Creed Graphic Novel, Assassin's Creed Vol. 1 Desmond, Assassin's Creed Vol. 2 Aquilus, Assassin's Creed Lineage, Assassin's Creed Renaissance, Assassin's Creed Brotherhood, Assassin's Creed The Secret Crusade, Assassin's Creed The Fall, Assassin's Creed Ascendance, Assassin's Creed Embers, Assassin's Creed Encyclopedia, and Assassin's Creed Revelations.