A few days ago, EA and Valve promised to show off an all-new multiplayer mode in Left 4 Dead 2. On Wednesday night, we trekked out to an underground location in San Francisco to see what all the fuss was about.

Upon arriving, we found eight PCs and eight Xbox 360s set up in two standard 4v4 versus mode configurations. That's exactly what we played for the first hour: Versus mode. The level up for grabs was set along a rural highway, leading into a run-down motel and its adjacent parking lot. In another area, we fought off (and fought as) the undead through the remnants of a local carnival. With the exception of some of the new zombie types (Charger, Jockey and Spitter), fighting through Versus mode was more or less the same as it was in the original game.

The Charger is built like a linebacker and has a primary attack that consists of him running down his prey. He's a straight line powerhouse so sidestepping out of the way isn't terribly difficult; however, if his attack connects, his victim is immediately knocked on his ass. The Jockey likes to ride his victim's head and take control of their movements. Although the Jockey doesn't cause a great deal of direct damage, he can steer the victim into the line of fire and cause indirect damage that way. Last, but not least, the Spitter does just what his name implies: He spits a targeted acid at his victim.

After about an hour or so of play, the games were paused and the systems restarted. This time around, Scavenge mode was the focus. A new gameplay type introduced for Left 4 Dead 2, Scavenge was designed with speed and intensity in mind. Sure, there could be some high tension moments, but it's not uncommon for a classic Versus mode game to last for longer than an hour. With Scavenge mode, that just doesn't happen.

The core concept behind Scavenge mode is collection. Our trust survivors need to collect 16 gas cans that have been strategically placed around the level and get them back to a generator. The undead hordes just need to stop the survivors. In order to ensure the pace is always set to 11, each round starts with a mere 90 seconds on the clock. Every time a survivor successfully returns a gas can to the generator, 20 seconds are added. If the clock runs down to zero, that's all she wrote, though there is an exception. As long as at least one survivor is holding a gas can, the clock can hit zero without ending the round. Should the gas can-toting survivor make it back to the generator safely, another 20 seconds are added to the clock. If the gas can is dropped, it is an instant game over.

Once the survivors have been killed, the two teams of four switch sides for the second half of the round. The new survivors simply need to beat the number of gas cans collected by the opposing team to win the round. Matches consist of three rounds, and the best two out of three are included in the score.

Playing with a group of other game journalists on a local LAN, rounds averaged 5-10 minutes each, with full matches taking 15-20 minutes at most. A few of the quicker matches barely hit 10 minutes. Because every session immediately dropped you into gameplay, there was little downtime. Unlike Versus mode or the campaign, Scavenge doesn't really feature "moments of calm." It's all chaos all the time, and that's most definitely a good thing.

The map we played on was the same run-down motel that we ran across in Versus mode. Here, the generator was stationed in the middle of the map, inside a drained pool. It had some safety barriers around the edges (can't have those little kids wandering in) that allowed for basic defense, but by and large, the generator was in the open. As a result, anyone trying to pour in a can of gas was best advised to have a buddy riding shotgun — preferably with a shotgun – for defense.

Getting to some of the gas cans also required a little forethought, as they weren't spread evenly throughout the level. Instead, the cans were scattered a bit unevenly, with some hiding inside motel rooms while others could be found outside. Two were even up high, on a billboard ledge. Our first instinct upon starting a round as a survivor was to make a mad dash for each can, but after playing for a short while, it becomes obvious that this isn't the most prudent move. Even gas can collection requires a little strategy.

Some of the cans are relatively easy to reach, but for those that were clustered in pairs in out-of-the-way locations, the smart thing to do was grab one can and toss it down to the ground before grabbing the second and returning it to the generator. Why throw around the gas cans, you ask? Quite simply, it saves time on the return trip. For example, if you can toss a can off its perch at the top of the billboard, you won't need to make a second trip all the way to the top. Instead, the second can will remain on the ground where you left it.

In a pinch, the gas cans can also be shot, resulting in a localized wall of flame. It's a nice way to clear out an advancing group of enemies, but the catch is that you destroy the can. Some of the zombie players can also ignite a gas can with a well-placed shot, so if you're holding a gas can in public, don't dawdle.

Scavenge mode was created with a specific purpose in mind, and it appears to have filled that role well. As an individual component within a larger overall product, Scavenge mode promises to keep the multiplayer options in Left 4 Dead 2 fresh and exciting, even for veteran players. We're looking forward to getting more hands-on time as soon as the final build is ready. In the meantime, if you want to dig up a for more details on Scavenge mode and the rest of the Left 4 Dead 2 experience, be sure to check out our interview with Valve's very own Doug Lombardi.