Last year was exceptionally strong for first-person shooters. Yet despite being one of the latest genre releases in the year, Call of Duty 4 towered over its competition. There are so many shooters released these days that it's hard to stick with an online community for more than a few weeks, but even months later, we're still obsessively playing COD4's addictive online mode with no end in sight. So we counted ourselves among the incredibly fortunate when we headed down to developer Infinity Ward's Southern California offices recently to check out the game's first downloadable map pack, which is coming later this spring.