If the core of a first-person shooter comes down to how fun it is to shoot, then Killzone 2 was already a shoo-in for this category. While the original Killzone's weapons were limp and unsatisfying, Killzone 2's are weighty, effective, and an absolute blast to shoot. Yet the improvements go far beyond the enhanced arsenal. Killzone's artificial intelligence was remarkably inept, but Killzone 2 exhibits some of the year's finest AI, another reason the action is so much more satisfying. And while its predecessor suffered from a variety of technical issues that marred its otherwise strong presentation, Killzone 2 is a technical marvel, stunning to both look at and listen to.