Left 4 Dead

On the surface, Left 4 Dead doesn’t look like it’s bringing all that much newness to the genre of first-person shooters. As one of four survivors in a city overrun by a zombie plague, you’ll have to shoot your way clear from safe house to safe house in missions that follow a horror-movie structure. But L4D really grabs by crafting a genuinely scary experience, thanks to a complex “AI director” algorithm that tweaks the music, narrative and visuals in accordance to how well you and your teammates play.

The AI director manages the zombie threat level, too, so expect to see more feral Hunter zombies or obese Boomer undead as you get better at staying alive; it’s possible to play the same missions and get a unique experience every time. Speaking of unique experiences, L4D also lets you play as the zombie types themselves, including one who uses vomit to attack. Those of us with alcoholic exes know how powerful weaponized puke can be.

EA/Valve. Xbox 360,$59.99