From Wikipedia
Jak II is a science fiction platform game developed by Naughty Dog. Released for the PlayStation 2 game console on October 14, 2003, the game is the sequel to Jak and Daxter: The Precursor Legacy and the second game in the Jak and Daxter series.
The game features new weapons and devices, new playable areas, and a storyline that picks up after the events of The Precursor Legacy. The game's plot is much darker then it's predecessor's, set in Haven City, a dystopia ruled under the questionable fist of Baron Praxis, who is engaged in a war against a techno-organic group of organisms known as the "Metal Heads". As in the previous game, the player takes on the dual role of recurring protagonists Jak and Daxter. There are also a new array of characters such as Torn, Erol, Krew, Kor, Ashelin, and Sig, as well as some returning ones, such as Samos and Keira.