Assassin's Creed: Bloodlines is a 2009 action-adventure video game developed by Griptonite Games and published by Ubisoft. It is the second spin-off installment in the Assassin's Creed franchise, and acts as a direct sequel to Assassin's Creed (2007). Beginning shortly after that game's events, Bloodlines follows Altaïr Ibn-LaʼAhad as he travels to Cyprus to eliminate the last remnants of the Templar Order and learn more about their plans. The game also explores Altaïr's relationship with Maria Thorpe, a Templar agent whose life he spared in the first game and who would eventually become his wife.

The game was announced by Sony at the E3 Conference in June 2009 as a new title for their PlayStation Portable console. Bloodlines was released in November 2009, concurrently with Assassin's Creed II and Assassin's Creed II: Discovery, and received mixed reviews from critics. The next spin-off in the series, Assassin's Creed III: Liberation, was released in October 2012.

Assassin's Creed: Bloodlines is an action-adventure, stealth game set in an open world environment. The gameplay is nearly identical to that of Assassin's Creed in terms of control style, although there were minor modifications to the control scheme, due to the lack of specific keys and buttons on the PlayStation Portable. Some features from the previous game, such as Eagle Vision, were removed.

One difference between the two games is the number of civilians present on the street. While the first game was filled with random civilians, Bloodlines has little to no civilians, explained in-game that the people were in a constant state of insecurity due to the new system of governance. Still, civilians will react to Altaïr's improper behavior, such as scaling buildings, and running around the streets.

Stealth in Bloodlines was downgraded due to the control scheme. Blending was also downgraded, due to the system platform. Although scholars are still present in-game, Altaïr can no longer use them as a way to hide. Although Altaïr can still blend, it only acts as a way to safely bypass guards without raising suspicion. Scaling the side of buildings was made easier and faster, resulting in simpler animations, again, due to the system's inferiority. High and Low profile movements are still present in-game, though they have been downgraded as well.

Taking the place of flags, a new collectible featured in the game are Templar Coins that can be used to upgrade the player's health bar, and the amount of damage a weapon can inflict. Three types of coins are present in game: Bronze, Silver and Gold, with Gold holding the highest value. Similar to the previous game, side-missions are available to players, such as saving civilians from Templar soldiers and performing specific tasks for allies of the resistance. The variety of tasks has been expanded, such as delivering letters, and intercepting couriers. In return, Altaïr will receive coins as a reward, instead of assistance from previous groups, such as scholars and vigilantes.

The game is primarily set on the island of Cyprus, where players can freely explore the cities of Limassol and Kyrenia. Due to the smaller size of the map, horseback riding was removed in Bloodlines. Like in the previous game, Altaïr can synchronize from high vantage points around the city in order to map out the city. Although the map itself is already drawn out, synchronizing will provide the locations of various side-missions.

Bloodlines features a few new assassination techniques and weapons. Weapons from the previous game are also present, such as Altaïr's sword, his hidden blade, throwing knives, and his fists. Assassinations are also similar to the first game, although the animation has been toned down to better fit the system. A new, yet very minor assassination technique has been added to the game, allowing Altaïr to pull opponents off of ledges, similar to Assassin's Creed II.