Kratos – God of War I – the plot/story line
For the next decade, Kratos traveled throughout Greece in service to the gods in hopes that they would forgive him of his crimes. While traveling through the Aegean Sea, Poseidon, god of the seas, commanded Kratos to destroy the Hydra.While Kratos battled, Zeus called forth Athena, the latter warning him of her brother's impending invasion of Athens. Although he was pleased that Athena chose Kratos to destroy Ares, he was concerned that he might become too powerful to control.
After Kratos defeated the Hydra, Athena told him that the gods would forgive his past if he could stop Ares from destroying Athens. Arriving in Athens, he encounters a man that says he is digging Kratos' grave, but that he will be there to help Kratos "when it seems like there's no hope." Kratos fought his way through the city and saved an oracle from death. In gratitude she revealed the means to kill a god - Pandora's Box.
Following the oracle's instructions, Kratos left Athens for the Desert of Lost Souls. He summoned Cronus, swung a chain across the Titan's face, and climbed to the summit where the temple lay. Ignoring the warnings of the Body Burner, Kratos entered it and retrieved Pandora's Box. Sensing Kratos' success, Ares hurled a broken column across the land towards the Temple of Pandora, impaling and pinning Kratos. Several Harpies took Pandora's Box back to Ares as Hades took Kratos.
Kratos managed to escape from the Underworld due to a mysterious rope. When he climbs the rope to the top, he finds that the gravedigger dropped the rope through the grave he had dug. When Kratos asks how this was possible, the grave digger responds cryptically "Athena is not the ONLY god following your progress."
While Kratos had been making his way through Hades, Ares had conquered Athens. Kratos caught up with Ares and took back Pandora's Box, unleashing its power. After a brief battle, Ares sucked Kratos into his own subconscious, making him relive the murder of his family. Kratos defended his family from numerous replicas of himself, causing Ares to use Kratos' weapons to kill his family.
After being transported back to Athens, Ares prepared to deliver the final blow. Kratos avoided the blow and grabbed the final gift from the gods: the Sword of the Gods. Kratos ran Ares through with his sword.
Athens had been saved. However, the nightmares continued to plague Kratos. Hoping to end his misery, Kratos made his way up to the Suicide Bluffs and flung himself off the cliff. However, a powerful force stopped him from falling and put him back on top of the bluffs. Athena offered him Ares' place as God of War. Kratos approached the empty throne and took his seat, becoming the brand new God of War.
As in Wikipedia