Killzone 2 is the third game in the Killzone franchise and continues the story two years after the events of the first two games. The gameplay consists of what the developers describe as Hollywood Realism, focusing on scripted, cinematic gameplay. The game is played entirely from the first-person perspective, except for the portions with vehicular combat with a tank and an exoskeleton. Next to the single-player campaign, there is squad-based multiplayer called Warzone with five different kinds of missions (Assassination, Search & Retrieve, Search & Destroy, Bodycount and Capture & Hold) based on seven kinds of classes. There is support for up to 32 players, with the addition of bots to fill the remaining spots.

Two years after the Helghast assault on Vekta, the ISA is taking the fight to the enemy's home world of Helghan. The ISA goal is direct: capture the Helghast leader, Emperor Visari, and bring the Helghast war machine to a halt. Assuming the role of Sev, a battle-hardened veteran and a member of the Special Forces unit Alpha Team, the player must lead a group of highly trained soldiers on a mission to take out the Helghast threat.