In addition to the individual games, two collections featuring remastered versions of both PS2 installments – God of War Collection – and both PSP installments – God of War: Origins Collection – have been released on the PS3 by Bluepoint Games and Ready at Dawn, respectively. Another collection – God of War Saga – released on August 28, 2012 for the PS3 features God of War I, II, III, Chains of Olympus, and Ghost of Sparta. With the exception of the mobile phone game, God of War: Betrayal, every installment in the series has been released on the PlayStation 3 and each main installment was released in the month of March. Merchandise promoting the series has been produced, including artwork, clothing, and toys. As of June 2012, the series has sold more than 21 million copies worldwide.
The central character of the series is Kratos, a Spartan warrior tricked into killing his wife and child by his former master, the God of War Ares. Kratos eventually kills Ares at the behest of the goddess Athena and takes his place as the new God of War, but is still haunted by the nightmares of his past. Kratos is eventually betrayed by Zeus, the King of the Olympian Gods. Revealed to be a demigod and the son of Zeus, Kratos now seeks revenge against the gods for their machinations. A series of attempts to free himself from the influence of the gods and the Titans and to exact revenge follow. Each game chapter forms part of a saga with vengeance as a central theme, and each game in the series is darker than its predecessor.