L4D2 promises to set a new benchmark for co-operative action games and become one of 2009's marquee titles, adding melee combat to enable deeper co-operative gameplay, with items such as a chainsaw, frying pan, axe, baseball bat, and more.

Introducing the AI Director 2.0, L4D's dynamic gameplay is taken to the next level by giving the Director the ability to procedurally change weather effects, world objects, and pathways in addition to tailoring the enemy population, effects, and sounds to match the players' performance. The result is a unique game session custom fitted to provide a satisfying and uniquely challenging experience each time the game is played.

In addition to the new campaign and boss monster L4D2 also includes "Mudmen," the "uncommon common" exclusive to the Swamp Fever campaign, and a few more of the 20-plus new items coming in the full product (cricket bat, AK47, and grenade launcher).

Featuring new Survivors, boss zombies, weapons, and items, Left 4 Dead 2 offers a much larger game than the original with more co-operative campaigns, more Versus campaigns, and maps for Survival mode available at launch.

Earlier rumors started floating around that the final two campaigns were the mall-centered Dead Center, and Hard Rain, which have now been confirmed by the achievement list.

Left 4 Dead 2 Achievements (50 total for 1000 points):

• PRICE CHOPPER 20: Survive the Dead Center campaign.
• MIDNIGHT RIDER 20: Survive the Dark Carnival campaign.
• RAGIN' CAJUN 20: Survive the Swamp Fever campaign.
• WEATHERMAN 20: Survive the Hard Rain campaign.
• BRIDGE BURNER 20: Survive the Parish campaign.
• STILL SOMETHING TO PROVE 35: Survive all campaigns on Expert.
• THE REAL DEAL 35: Survive a campaign on Expert skill with Realism mode enabled.
• CONFEDERACY OF CRUNCHES 30
• Finish a campaign using only melee weapons.
• HEAD HONCHO 15: Decapitate 200 Infected with a melee weapon.
• CLUB DEAD 15: Use every melee weapon to kill Common Infected.
• CHAIN OF COMMAND 15: Kill 100 Common Infected with the chainsaw.
• TANK BURGER 30: Kill a Tank with melee weapons.
• SHOCK JOCK 30: Revive 10 dead Survivors with the defibrillator.
• THE QUICK AND THE DEAD 30: Revive 10 incapacitated Survivors while under the speed-boosting effects of adrenaline.
• ARMORY OF ONE 15: Deploy an ammo upgrade and have your team use it.
• BURNING SENSATION 15: Ignite 50 Common Infected with incendiary ammo.
• DISMEMBERMENT PLAN 20: Kill 15 Infected with a single grenade launcher blast.
• SEPTIC TANK 15: Use a bile bomb on a Tank.
• CRASS MENAGERIE 20: Kill one of each Uncommon Infected.
• DEAD IN THE WATER 20: Kill 10 swampy Mudmen while they are in the water.
• ROBBED ZOMBIE 15: Collect 10 vials of Boomer vomit from infected CEDA agents you have killed.
• CL0WND 15: Honk the noses of 10 Clowns.
• FRIED PIPER 15: Using a Molotov, burn a Clown leading at least 10 Common Infected.
• LEVEL A CHARGE 15: Kill a Charger with a melee weapon while they are charging.
• ACID REFLEX 15: Kill a Spitter before she is able to spit.
• A RIDE DENIED 15: Kill a Jockey within 2 seconds of it jumping on a Survivor.
• STACHE WHACKER 15: Prove you are faster than Moustachio.
• GONG SHOW 15: Prove you are stronger than Moustachio.
• GUARDIN' GNOME 30: Rescue Gnome Chompski from the Carnival.
• WING AND A PRAYER 30: Defend yourself at the crashed airliner without taking damage.
• SOB STORY 30: Navigate the sugar mill and reach the safe room without killing any Witches.
• VIOLENCE IN SILENCE 30: Navigate the impound lot and reach the cemetary safe room without tripping any alarms.
• BRIDGE OVER TREBLED SLAUGHTER 30: Cross the bridge finale in less than three minutes.
• HEARTWARMER 20: In a Versus round, leave the saferoom to defibrillate a dead teammate.
• STRENGTH IN NUMBERS 15: Form a team and beat an enemy team in 4v4 Versus or Scavenge.
• QUALIFIED RIDE 15: As the Jockey, ride a Survivor for more than 12 seconds.
• BACK IN THE SADDLE 15: As the Jockey, ride the Survivors twice in a single life.
• RODE HARD, PUT AWAY WET 20: As the Jockey, ride a Survivor and steer them into a Spitter's acid patch.
• GREAT EXPECTORATIONS 15: As the Spitter, hit every Survivor with a single acid patch.
• A SPITTLE HELP FROM MY FRIENDS 15: As the Spitter, spit on a Survivor being choked by a Smoker.
• SCATTERING RAM 20: As the Charger, bowl through the entire enemy team in a single charge.
• MEAT TENDERIZER 20: As the Charger, grab a Survivor and smash them into the ground for a solid 15 seconds.
• LONG DISTANCE CARRIER 15: As the Charger, grab a Survivor and carry them over 80 feet.
• BEAT THE RUSH 15: In a Survival round, get a medal only using melee weapons.
• HUNTING PARTY 15: Win a game of Scavenge.
• GAS GUZZLER 20: Collect 100 gas cans in Scavenge.
• CACHE AND CARRY 20: Collect 15 gas cans in a single Scavenge round.
• SCAVENGE HUNT 15: Stop the enemy team from collecting any gas cans during a Scavenge round.
• FUEL CRISIS 15: Make a Survivor drop a gas can during overtime.
• GAS SHORTAGE 20: Cause 25 gas can drops as a Special Infected.