Developed by Guerrilla, in conjunction with Sony Computer Entertainment Europe and Sony Computer Entertainment Americas Santa Monica Studios, Killzone is a squad-based, first-person shooter, set in the near future during a period of planetary colonization. Drawing inspiration from classical military conflicts of the 20th century, Killzone captures the intense reality of warfare between the ISA Command and a ruthless, militaristic separatist faction called the Helghast.

Featuring four playable characters, Killzone provides several gameplay modes including single-player, multiplayer (team based and competitive) and online play for up to 12 players. Players can equip themselves with an armory of more than 27 different weapons inspired from todays modern weaponry. In particular, there are 21 first-person weapons that the player can carry, five emplaced weapons, and hand grenades. More than 11 intricately detailed environments showcase the harsh setting of a war-ridden planet, coupled with a unique graphical style designed to capture the grit and realism of intense military engagements.

For years, the success of planetary colonization has resulted in several planets to become inhabited by humans. While the majority of colonies have aligned to form the ISA, the Helghast, a ruthless, militaristic separatist faction have distanced themselves secretly planning to scale an all out war.

Killzone takes place during the initial Helghast blitzkrieg of the nearby colony of Vecta. As Vecta Citys orbital defenses mysteriously fail, the Helghast have been able to land and deploy their troops rapidly and with ease. As the planetary defense forces become overrun and scattered into the city, the initial objective as an ISA member is to escort a high-ranking official to an evacuation point.