These are the different Xbox 360 achievements that you’ll get as you kill different types of mobs in Left 4 Dead 2:
To get this one, you have to kill 15 mobs with one single grenade launcher blast. The easiest place to get this one is on the Dark Carnival finale. You can get the grenade launcher on the center of the stage and you’ll find that the bile you need is on one of the speakers here too. Then, throw the bile and blast the mobs when they come up to get it. Do this one while you’re playing with friends - otherwise, the AI in the game will take all the kills and you won’t get the achievement.
To finish this Xbox 360 achievement, you have to kill one of each of the different special infected. Of course, you do have to go through all of the levels to get this one as some are only on certain levels.
Dead in the Water
Just kill off 10 Swampy Mudmen when they are still in the water. Play the Swamp Fever level a couple of times and you’ll easily pick up this Xbox 360 achievement for Left 4 Dead 2.
To get this one, you simply have to kill any common mob with each of the melee Left 4 Dead 2 weapons: axe, cricket bat, crobar, frying pan, buitar, katana, machete, and the nightstick. Believe it or not, but the baseball bat and the chainsaw don’t count.
Chain of Command
To get this Xbox 360 achievement, you just have to kill any 100 normal mobs with the chainsaw.
This one is a bit hard, and you’ll have to have help. To get this L4D2 achievement, you have to actually kill a tank with melee weapons only. So, you can have everyone beat it with a melee weapon or you can hit and pull a tank during the finale as you’re going to the escape vehicle. Then, the computer will automatically kill off the tank when the cutscene starts.
Harder Kill Achievements
Confederacy of Crunches
This one is fun but hard, as you have to go through a whole level (any level) with only melee weapons - so I would NOT recommend doing this one in Realism mode at any time. The easiest way to complete this one is to not pick up any guns at all, and don’t use your pistol even if you get into real trouble. Otherwise you have to start all over, but only you have to use the melee weapons - others in your group can use guns. You can throw things when you do this Xbox 360 achievement, just nothing gun-wise. The easiest level to use is Dead Center.
You should be able to start on this one while you’re doing Confederacy of Crunches and throughout the game, as it means that you have to decapitate 200 infected with only a melee weapon - no guns. The best melee weapon to do this one with is the baseball bat, even though it’s not any type of knife.
During Dark Carnival, you need to find a place where a clown is leading 10 or more normal mobs around and burn them with a molotov. So, when you’re on this level, just lob your molotovs at clowns when there are lots of mobs around them.
Level a Charge
This one is a bit hard to do solo, so if you can get a friend to play with you do so. You have to take out a charger with only a melee weapon while they’re charging. So, the best way to do it is to time it right so that you sidestep a charger while they are coming at you and then whack them as they go past. The best thing to do is to have someone shooting at them while you’re doing this so you can get the two major hits it takes to kill one.
This one is gross but not too hard if you’re a good shot as all you have to do it take out a Spitter before she can spit on you. So, just shoot every one of them until you get it - which should be right away.
A Ride Denied
This is a funny one, as you have to deal with the Jockey special infected. Simply kill one in the first 2 seconds of one of these guys jumping on one of the survivors. This is another one of the Xbox 360 achievements that you should easily get.
Violence in Silence
To do this one, you have to go through the impound lot and then get to the safe room in the cemetary without setting off any of the alarms along the way. So, this is where you’ll want the computer players with you as they all have perfect aim. Go through here, using melee weapons, in Parish level, without jumpin on any of the orange colored or smoked into any of the cars. Get to the safe room and you’ll get the achievement.
Bridge Over Trebled Slaughter
This is done in the finale of Parish - the final level. To do this one, you have to get across the bridge in less than three minutes, which is pretty darn hard. So, you need to have all human players here - no computer controlled guys (or gals). Then, when the bridge drops, run your butts off for the other end. You will need tons of adrenaline here, but don’t use it yet - you want to use it toward the end of the bridge when the mobs will try to swarm you and you don’t want to use the immunity that you get to the infected’s slow down just yet. Now, there is a tank halfway across, which is the hardest part and if you can’t avoid him, it’ll cost you the Xbox 360 achievement here. Get around him somehow - don’t fight him or get hit. If you find that you’re running out of adrenaline, there are several on the trucks as you go, so you can use the few seconds it takes to get them if you need them.