@slowmo
you have to get the right mods.
Ok, first off Killzone 2 had beautiful graphics.... but the gameplay kind of lagged for me. You had a teammate basically the whole game through, but why no co-op?
I myself would rather have co-op. Killzone 2 was utter crap(to me) because there was no co-op.
and it has to have the same engine to play with halo 3