Most games don't sport a native 1080p resolution. It's kinda tough to do.
As for Killzone 3 , which features a maximum high-definition resolution of 720p, there's a good reason why the higher option was out of the question. Guerrilla Director of Production Arjan Brussee has stated it was simply "not possible" for the sake of production quality. Thing is, there's just "too much happening" for 1080p and Brussee says gameplay would be diminished if the team had pushed the visuals up a notch. It's always a matter of designer choice; the Uncharted series doesn't run in 1080p, either, and yet, we hear no complaints from anyone, as it's widely considered to be the best-looking franchise of the generation. Brussee's explanation of "too much going on" may sound a little vague, but you have to remember – from a development standpoint – what it would mean to build every last on-screen effect in 1080p…
Killzone 3 does support 3D, however. So if you absolutely must get more involved in your gaming, you can always slap on the glasses.
Related Game(s): Killzone 3