Intro Scene

The intro scene for Left 4 Dead was a first for Valve Corporation, as they've never had an opening cutscene in their past games. As such, it went through many changes throughout production. Originally, Francis and Zoey were shown to have a sort of romantic tension between each other, and Louis would be a kind of comedic relief. However, this was found as "distracting" and therefore removed.

http://www.youtube.com/watch?v=UF1HVlcXBmA

Transcript
2 WEEKS AFTER FIRST INFECTION

[ Focus in on deceased hand, thumb missing, flies crawling around on it ]

[ The group walks up into shot ]

Bill: Hold up!

[ Bill crouches, scooping up green goo ]

Bill: Ain't see anything like this before...

Francis: Jesus. Don't let that stop you from smearing it all over yourself.

[ Bill glares at Francis, gets up, and wipes the goo on Francis' vest ]

Bill: They're changing.

Francis: God ... damn it Bill! Augh, it stinks!

[ Francis wipes the goo off while Louis chuckles ]

[ Muffled crying... ]

Zoey: Someone's still alive!

[ Zoey and Bill open a nearby door to a pitch black room ]

Bill: Over there.

[ Zoey turns her flashlight on and pans it across the room ]

''[ The crying gradually grows louder ... ]''

Zoey: Hello? Hello? Hey, it's okay ... we're gonna --

[ Lightning flashes; the Witch is seen crouching in a corner, and is identified as the source of the sobbing ]

Bill: Lights off!

[ Outside, Louis sees a horde approaching; he and Francis open fire ]

Louis: Oh shit! Shit! Shit! Shit! They're coming!

[ Louis shines his flashlight over Zoey and Bill's shoulders, inadvertently startling the Witch ]

Louis: What the-

Zoey: Run like hell!

[ Zoey and Bill run out of the room while Louis slams the door shut ]

[ Louis fires at the Witch's arm, which claws a hole in the door, while the rest fight the horde ]

Louis: Do you like that?!

Francis: Stick together!

[ Smoker grabs Bill and hangs him in mid-air ]

Francis: Hang on!

[ Francis shoots the Smoker, killing it ]

Zoey: Guys ...?

[ Francis fires his shotgun at two approaching Infected ]

Francis: Merry Christmas.

[ Zoey unstraps a pipe bomb from her waist ]

Zoey: Fire in the hole!

[ The bomb flies in slow motion through the air, it lands several yards away where it explodes, reducing the remaining Infected to a fine red mist as The Survivors huddle behind cover ]

[ A helicopter is seen flying overhead through the street, which Louis pursues ]

Louis: Hey! We're over here! We're not infected! Down here!

[ The helicopter proceeds, not seeing him ]

Louis: ... Damn it.

[ A Hunter leaps from a nearby building and pins Louis to the ground ]

[ Zoey knocks the Hunter off Louis and opens fire with dual pistols as it staggers back; Louis delivers a final headshot with his own pistol, setting off a car alarm ]

Bill: Oh, this is gonna get bad.

[ Waves of infected pour over surrounding fences and streets; a Tank is heard roaring in the distance; a car flying through the air heralds its approach ]

Louis: Run ... or shoot? ... Run or shoot?!

Bill: Both!

[ The group clamors into a nearby alley, continually shooting at the Tank and its accompanying horde ]

[ Louis points to a ladder leading up a fire escape ]

Louis: Get to the roof!

Francis: Go! Go! Go!

[ Francis stops at the base of the ladder, aiming his gun at the Tank ]

Francis: Come on, come on!

[ Just as the tank is about to smash Francis, Bill opens fire; the tank retaliates by hurling its fist at him; he dodges, sending it through a brick wall; the enraged Tank grabs a slab of concrete and hurls it at Louis and Francis, who are now scrambling up the fire escape ]

Louis: Heads up!

[ Bill reaches for the ladder; Zoey is seen staving off the horde from above ]

Zoey: Go! I'll hold them off!

[ The Survivors climb the stairs to the roof of an apartment; the Tank climbs up the fire escape, but it gives way under its weight, nearly taking Zoey with it ]

Zoey: Francis!

[ Francis grabs Zoey by the arm in time to pull her over the ledge ]

[ The exhausted Survivors take a moment to catch their breath ]

Louis: We made it! I can't believe we made it!

Bill: Son, we just crossed the street.

[ Bill pauses to light a cigarette ]

Bill: Let's not throw a party 'til we're outta the city.

Beta intro

 * 8/7/2008 - http://www.youtube.com/watch?v=RINyhvIgdRg
 * 25/7/2008 - http://www.youtube.com/watch?v=PQ2vqE0zc3E&feature=related
 * 4/9/2008 - http://www.youtube.com/watch?v=_OCR_H0ricQ&feature=related

Trivia

 * Bill is the only one of the Survivors to have a tier 2 weapon during the intro.
 * Both of the pistols Zoey holds have flashlights on them.
 * Bill tells Zoey to turn of her light when she points them at the Witch, possibly hinting that Bill has seen them before the others, though it is also possible he simply saw she was infected or noticed her claws.
 * Although Louis is pinned by the Hunter for several seconds, there are no signs of blood or scratches on him, he doesn't even seem to be hurt.
 * Near the end, when the Survivors are mounting the fire escape, Zoey shoots an Infected's head off with a pistol. In actual gameplay, the pistol doesn't have enough power to do so.
 * Strangely, as soon as the survivors get to the roof, it becomes completely silent, despite the Tank below. This is possibly just to add a tone of relief.