I gave the disc a good clean, and Killzone works great now. I'm stuck on an area though, not because I suck at aiming, but because it is relentless. A group of helghast can kill you in a matter of seconds, even considering they have the worst aim ever.
The aim feels kinda iffy to me, but I won't complain that much. It works, and it's responsive. Something just makes it inferior to what Halo and CoD have, though I can't even tell what it is.
I also got Heart Gold, with my brother getting Soul Silver. It's great, but I just wasted my whole day on the voltorb flip. It seems pretty long since I now take small breaks from video games.