SoftUK are selling "Assassins Creed: Directors Cut Edition" for the PC for £17.99.
Use the code "Cheap Games" (without quotes) to get free delivery.
You can get cashback via some sites (e.g. 2% Free Fivers, making it £17.63). You can also get 6% cashback through SoftUK's 'Collector' program
Next best in-stock price seems to be £19.99 from ShopTo.
The first game in the Assassins Creed franchise is set in 1191 AD, when the Third Crusade was tearing the Holy Land apart. Shrouded in secrecy and feared for their ruthlessness, the Assassins intend to stop the hostilities by suppressing both sides of the conflict. Players, assuming the role of the main character Altair, will have the power to throw their immediate environment into chaos and to shape events during this pivotal moment in history.
Be an Assassin Master the skills, tactics, and weapons of historys deadliest and most secretive clan of warriors. Plan your attacks, strike without mercy, and fight your way to escape.
Realistic and responsive environments Experience a living, breathing world in which all your actions have consequences. Crowds react to your moves and will either help or hinder you on your quests.
Action with a new dimension total freedom Eliminate your targets wherever, whenever, and however. Stalk your prey through richly detailed, historically accurate, open-ended environments. Scale buildings, mount horses, blend in with crowds. Do whatever it takes to achieve your objectives.
Relive the epic times of the Crusades Assassins Creed immerses you in the realistic and historical Holy Land of the 12th century, featuring life-like graphics, ambience, and the subtle, yet detailed nuances of a living world.
Intense action rooted in reality Experience heavy action blended with fluid and precise animations. Use a wide range of medieval weapons, and face your enemies in realistic swordfight duels.
Next-gen gameplay The proprietary engine developed from the ground up for the next-gen console allows organic game design featuring open gameplay, intuitive control scheme, realistic interaction with environment, and a fluid, yet sharp, combat mechanic.