Killzone Liberation is the sequel to the PS2 game Killzone. New to the franchise is the top-down/third-person perspective, instead of the PS2's first-person pure FPS approach. During the action, you can switch to a tactical overview to plan your actions. The screen zooms out and the actions are slowed down, while icons pop up to show the different actions and objectives. The game comes with a full range of Ad Hoc settings for multiplayer, with co-op and competitive play modes included, such as Deathmatch, Assault and Capture the Flag for up to six players.

Two months after the events of Killzone, most of southern Vekta is still under Helghast control. The rules of war are cast aside when the Helghast General, Metrac, employs increasingly brutal measures to seize the initiative and strengthen his position. Reprising the role of Templar, the player is sent on a covert operation to save hostages captured by Metrac, while ISA troops continue the fight for liberty.