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Small Achievement Map

To load into this, open your console (with tilde ~ or grave `) and type in "map achievementtime". So long as you don't enable cheats, you can get the achievements with this.

My first foray into mapping, this map will provide you with five achievements with ease.
The achievements are:
Tank Burger (Kill a Tank with melee weapons only)
Til It Goes Click (Using the M60, kill 25 infected without letting go of the trigger.)
Barrel Rolled (Kill a Special Infected with an exploding barrel.)
Elephant In The Room (Revive an incapacitated teammate while a Tank is nearby.)
Level A Charge (Kill a Charger with a melee weapon while they are charging.)

I did also try and make one room give you Killing Them Swiftly To This Song, but it appears that the achievement is locked to The Passing. If you need this achievement, head to the second map and use the jukebox until you get the achievement. You're listening for a slow song, called Save Me Some Sugar. It's good. Listen to it.

The Tank Burger room has a strange setup with triggers, so the button doesn't work like a button. Just sort of rub up against the button until a tank spawns. You'll want to close the door for this one, as your teammates' gunshots will deny the achievement!

Til It Goes Click spawns 30 infected for good measure, since L4D2 seems to have a thing where if you're not looking at a group of zombies and they can't get to you then they get culled by the director. There's no director in this map so they won't go anywhere and can't get to you anyway, so whatever.

Barrel Rolled is a little finicky, and took me a couple tries to get it. I'd suggest that you shoot all of the barrels as quickly as you can, since the charger inside will move about seemingly randomly, which means it might go into a certain corner and just not die in the right way. When you do shoot the barrels, it won't die immediately, and that's completely normal. The fire will kill it and you should (hopefully) get the achievement. If not, reload the map, since I couldn't find out how to respawn explosive barrels.

Elephant In The Room was realized by someone in the comments - thankyou! To get this, use one of the map's weapons to knock an AI teammate down. Then, activate the tank spawn and pick them back up again.

Level A Charge requires you to kill a charger with a melee weapon while they're charging. It's a timing thing, but turns out this map makes it a little easier. Shoot the charger in the hand a few times (I recommend about 7-8!), then get close and wait for him to charge. Swing and enjoy your achievement.
Thanks to Mi mama me pega and StayPositive for discovering you can get this achievement!

I spent four hours making this for three achievements, but it can be used to get five.