So what's actually been changed for this sequel? Well, the most obvious new addition was the melee combat, with frying pans and axes available in the demo we played. They were only effective within close proximity to the enemy, but, boy, are they effective when you are. The axe is capable of lopping off limbs (dismemberment is another new feature of the game), while the pan makes a highly satisfying thud on impact. The most interesting melee weapon has yet to be shown--the chainsaw is an amazing prospect, so Valve is making us wait until later in the year before we get our hands on it.

Luckily, we were able to sink our teeth into plenty of other new features. There are now weapon upgrades available at random points in the game--we came across an incendiary upgrade that made our machine gun bullets set fire on impact. You only get about 50 of these fire-spewing shots per upgrade, but they certainly make short work of the standard zombies. Then there's the brutal new enemy called the Charger, who picks you up and slams you to the ground repeatedly until your teammates come to rescue you.

The game was at its most tense during the gauntlet run--a term Valve used to explain the bridge section at the end of the level we played. Basically, a never-ending mass of zombies stand between you and the escape helicopter, so you have to work with your teammates to fend off the horde while slowly making your way across the bridge. Despite a liberal amount of gun turrets and ammo stockpiles, it's incredibly difficult to make it across, and if one of your team members die, there's no way to bring him back into the game. No wonder we died a few times trying to make it across here, but we loved the difference this made to the end of the level, as well as the tension it created.