gods and that he and Atlas will meet again. Kratos then rides the Sun Chariot back to the mortal world and into the sky as Morpheus retreats. In a post-credits scene, Kratos is still riding Helios' chariot back into the sky and after seeing the return of the Sun, Kratos loses consciousness from the exertion and plummets to the ground. At the last moment, Kratos is saved by Athena and Helios, and Athena tells Helios that "He will live." Development Game developer Ready at Dawn pitched the idea of a God of War game for the PlayStation Portable to Santa Monica Studio soon after the original God of War launched. In February 2007, Ready at Dawn posted a teaser featuring "Coming Soon" in the God of War font. An editor from 1UP obtained an early copy of God of War II and posted the game's instruction manual, featuring a one-page teaser with "PSP" in the Omega symbol and stating "Coming 2007". On March 12, 2007, God of War II was launched at the Metreon: God of War II Game Director Cory Barlog officially confirmed the development of Chains of Olympus, stating "It is its own story that connects to the overall story. God of War, God of War II, and then if all the stars align God of War III will be the telling of a trilogy. This PSP story will be a further fleshing out." An initial trailer for Chains of Olympus was released on April 25, 2007, coinciding with the announcement of a demo on UMD—the optical disc medium for the PSP. The trailer is narrated by voice actress Linda Hunt. God of War: Chains of Olympus uses a proprietary, in-house engine referred to as the Ready at Dawn engine, which expanded on the engine created for their previous game, Daxter (2006), to include a fluid and cloth simulator. The camera system was modified to cater to the fixed cinematic camera for God of War gameplay, and the lighting system was reworked to aid in presenting realistic graphics. The game was originally designed for the PlayStation Portable's restricted 222 megahertz (MHz) processor. Ready at Dawn repeatedly contacted Sony regarding increasing the clock speed of the PSP on account of the difference to the game and had developed a version of the game with higher speed. Sony released a firmware upgrade that allowed games to use the full 333