"God of War is a series of action-adventure video games based on Greek mythology. The three main installments in the series were developed by Sony Computer Entertainment's Santa Monica division, while Ready at Dawn Studios developed an installment on the PlayStation Portable and Javaground developed an installment for the mobile phone. The series made its debut in 2005 on the PlayStation 2 with God of War. A sequel, God of War II, was released also on the PlayStation 2 in 2007. God of War: Betrayal was released for the mobile phone in 2007 and takes place immediately after the first installment. In 2008, a prequel to God of War, God of War: Chains of Olympus, was released on the PlayStation Portable. God of War III released in 2010 for the PlayStation 3, and is the last in the current story arc. However, it will not be the last God of War game."
Source: Wikipedia, "God_of_War_(series)", available under the CC-BY-SA License.