Dark Carnival

Dark Carnival is the second campaign of Left 4 Dead 2, that takes place at Whispering Oaks carnival. It starts off on a highway with the Survivors heading towards a Ferris wheel in the distance, passing through a motel complex, and eventually reaching the Whispering Oaks carnival. It is the third Left 4 Dead 2 campaign to be announced by Valve.

Trivia

 * Dark Carnival is similar to the comedy-horror film Zombieland, where the climax takes place in a carnival, and the zombies are alerted by rides being turned on.
 * It may also be a reference to House of the Dead: OVERKILL, in which the protagonists had to shoot their way out of an infected carnival.
 * A third possible reference is that it could be a reference to the rap artists Insane Clown posse. Said artists often mention "The Dark Carnival" in their music, and wear face paint of evil clowns.
 * Dark Carnival is host to a new Uncommon Common Infected, the Clown Infected whose unusual ability is to attract nearby Infected with his squeaky shoes.
 * There also appear to be Infected with T-shirts that read "STAFF", implying they were working at Whispering Oaks when the Infection struck.
 * Dark Carnival's poster is the first poster to feature an infected, as well as the first to be in landscape position, as opposed to every other campaign poster.
 * Coach's and Ellis' clothes have changed in design yet again.
 * The infamous Gnome from Half Life 2: Episode Two makes an appearance in the poster, just between Ellis' legs. It appears to serve the same purpose, as an achievement and unlocks an avatar reward requires the gnome to be won from one of the mini games in the carnival.
 * The tagline in this campaign obviously refers to the height check carnival operators perform on people to make sure they can ride on certain attractions safely. This tagline may have been influenced by suggestions made on the official forums.
 * One of the safe rooms is located at the beginning of the "Tunnel of Love."
 * In the dialogue before the campaign, it reveals that it was Ellis' idea to go on to the highway, and Coach used to go to Whispering Oaks as a kid. It is later revealed that Ellis and Coach really liked the place when they were young during the campaign, because as you go through areas, they will talk about the carnival.
 * This is the campaign used when Valve revealed Scavenge Mode.
 * The car at the start of the campaign is now a race car, rather than a police car, making it obvious that Dead Center's finale will be used in Scavenge mode, due to it being seen as the object the Survivors must fuel in some of the screenshots.
 * Dark Carnival's finale seems to be one of the strangest - it takes place at a big stadium where a famous band was about to have a concert. Survivors have to set off the fireworks and/or say something in the microphone to attract a helicopter.
 * Dark Carnival's music.
 * One of the carnival's mascots, "Moustachio," makes an appearance in a select few mini-games. If the player scores a high enough score, they will unlock an achievement. Additionally, the shooting gallery mini-game unlocks Gnome Chompski, which is the gnome from Half Life 2: Episode Two.
 * Moustachio is the star of two achievements, both of which are found in stage 4: The Barns. First, as soon as you leave the safe house, you will see a test-your-strength game. Take adrenaline and melee the game's lever. The weight will fly out of the machine, netting you the Gong Show achievement. Warning, doing this causes a Panic Event.
 * Next, go a little further through. You should see a whack-a-mole type game called "Stache Whacker". Activate it. Shoot the Moustachios as they pop out. You can keep pressing continue. Once you hit about 45, the machine shorts out and spits tickets at you. You've won! You get the achievement Stache Whacker. Warning, this also causes a Panic Event.
 * The helicopter pilot that picks you up has a similar model as the helicopter pilot in the original Left 4 Dead, and ends in a similar fate.