The Electronic Safety Review Board has predictably rated Killzone 2 M for Mature Audiences, citing "Blood and Gore, Intense Violence, Strong Language".  However, in it's explanation for the rating, it may have spoiled a few significant game moments.  It reads "This is a first-person shooter in which players are members of an elite military unit whose mission is to quell an intergalactic threat and disarm a stockpile of seized nuclear weapons. Combat is frequent and fast-paced, as players use a variety of firearms (rifles, machine guns, and shotguns) and explosives (grenades and rocket launcher) to kill enemy soldiers. Red blood spray emits from enemy soldiers when shot, and weapons such as sniper rifles and shotguns can be used to decapitate them. Post-mortem damage can be inflicted on soldiers’ bodies, resulting in pools of blood on the ground. During one cutscene, a gravely wounded character retrieves a pistol and shoots himself in the head. The game contains strong profanity (e.g., “f*ck,” “sh*t,” “a*shole”) in the dialogue".

So, now we know you will be disarming nukes in KZ2, and at least one character commits suicide.  Thanks for the spoiler alert, ESRB!