You have got to be kidding me. Killzone 2 was a generic regenerating health dudebro shooter.
In Killzone 1 you had multiple characters with different personalities and guns/gameplay styles with interesting character interaction to boot. They basically robbed everything unique about Killzone 1 in order to go after the Call of Duty crowd.
To Rosa-You are young and I am older; you are hopeful, I am not-Enjoy life ere it grows colder-Pluck the roses ere they rot. -Abe Lincoln