Halo 2 E3 demo

The Halo 2 E3 Demo was a real-time demonstration of early plans for Halo 2's Outskirts and Metropolis levels. It was shown at E3 2003, and showed some designs for Halo 2, including ODSTs, Battle Rifles (which were originally going to be single-shot), Dual-Wielding, SMG's, Brutes, the Gauss Warthog, and many other things.

Plot
The Master Chief is en route to a UNSC field command post turned field hospital to assist the marines in destroying an artillery cannon and securing the area. The Pelican lands and Master Chief exits with a few ODST's to be introduced to Cpl. Perez who takes him through the field hospital to where Sergeant Banks is.

The Master Chief proceeds through the camp witnessing the new animations of allied AIs. He then passes through a destroyed building housing a Marine heavy Machine gun team and Sergeant Banks. Both are pinned down by Covenant forces. The Sergeant then calls in an airstrike on the artillery cannon. A flight of Longsword fighters promptly complies, launching a successful bombing run on the cannon. After the airstrike has occurred Banks gives the player his SMG, an introduction to the new feature of Dual-Wielding. Using his new weapons, the Chief clears the area of Covenant troops before moving over a pile a debris and into an open street.

In the street there is a packed group of about seven Jackals with shields. Upon spotting the Chief they form a phalanx and begin to open fire with their plasma pistols. After a few moments of shooting, the group of Jackals are splattered by a pair of Warthogs. One of the Warthogs is the new Gauss Warthog, the driver instructs the Master Chief to man the Gauss Cannon on the back. Upon the Chief entering the turret, Warthogs drive around the street areas which are incidentally quite similar to the streets before the Scarab attack in the Halo 2 level, Metropolis. After the Chief destroys a few Shadows and Ghosts, the Warthog is boarded by a Brute who kills the Marines in the passenger and driver seat, prompting the Chief to exit the vehicle to take action against the boarder.

The Master Chief quickly kills the Brute and a few of his comrades with his battle rifle before being alerted by Cortana of a fast approaching Ghost. Chief proceeds to board this vehicle by hijacking the Ghost, introducing yet another new Halo 2 feature.

The Chief proceeds to wreak havoc on the Covenant troops in the area before he is instructed by Cortana to escape the area via a tunnel which leads to a bridge. The demo then cuts then changes to a cutscene of two Brutes on Ghosts chasing the Chief through the tunnel. As a sign declaring "Highway access denied" flashes, the automatic doors at the end of the tunnel begin to close. In response to this small crisis Master Chief speeds up, barely making it through the remaining space between the closing doors, although in the process his Ghost crashes, disgorging him upon the ground. However the two pursuing Brutes are not so lucky. The door closes completely before they get to it and a shot from the outside of the tunnel shows the two explosions caused by the crash of the Brutes' Ghosts.

Just after Cortana points out a Covenant ship in the sky, a barrage of glowing drop pods begin to land around the Chief. Elites step out of these Drop Pods and draw their Energy Swords. Chief responds holstering one of his SMGs and charging up a Plasma Grenade. Cortana, noting Chief's action, teasingly says "bet you can't stick it" to which the Master Chief responds "You're on." As he lunges forward to toss the grenade, the demo ends.

Transcript
eoqGLS1U6GQ (Fade in on a massive building complex that dominates the sky)

'''NEW MOMBASA. EAST AFRICAN PROTECTORATE'''

(A Pelican zooms into view. We see the Master Chief)

Cortana: It took two in the nose then dropped into the atmosphere.

Master Chief: Who was first contact?

Sergeant Johnson: 405th out of Diego Garcia.

(Zoom out. We see the Pelican flying over the cloud layer)

Sergeant Johnson: But, don't expect a big welcome; the Covenant wiped most of them out before they hit the ground.

(The Pelican drops right into the city)

(Fade to white)

(Fade in. We see two marines looking on the LZ. Plasma mortars fly over the air above)

Spotter: Immediate. Grid Kilo 23 is hot. Recommend mission abort.

Pilot(O.S.): Roger, recon.

(The Pelican flies overhead)

Pilot: It's your call, Sarge.

Sergeant Johnson: We're going in. Get tactical, Marines!

(In the back of the Pelican, We see ODSTs getting their weapons ready)

Cortana: Covenant ground forces own this city. We'll need to deal with them before we can kill that cruiser.

(The Pelican lands smoothly on top of the government building )

Sergeant Johnson: Pile out! Go! Go! Go!

(The Master Chief hops out)

Sergeant Johnson (O.S.): I'll evac the wounded. Keep me posted, Cortana.

Cortana: Of course, Sergeant.

Marine #2 (To the Master Chief): Sir, Corporal Perez, A- Company. CP is this way.

(Master Chief follows the marine through a field hospital)

Marine Medic: Must be seeing things, guess the brass do give a shit. (Referring to the Master Chief arriving)

Marine Medic #2: Come on, come on! Stay with me marine!

Marine Medic #3: No tags. Hang two units, O-neg, and he needs an airway.

(The Marine stops at a wounded Marine)

Marine Medic #4: I'm calling it, 1900.

Marine #2: The Lieutenant got hit as soon as we dropped in.

Cortana: Who's in charge now, Corporal?

Marine #2: Sergeant Banks, Ma'am. He's pinned down out front. C'mon. I'll show you.

(Master Chief follows the Marine yet again. He walks into a building, up the stairs. You hear gunshots)

Marine #3: No, no! Behind that ST. Yeah, yeah, yeah! Three more! Coming left.

Marine #4: I'm running low, man!

(Master Chief follows the Marine to another part of the building)

Marine #2: Parsons!

Parsons: Yeah?

Marine #2: Is it clear?

(Giant explosion)

Private Parsons: You tell me!

Marine #5: Friendlies, moving out! Covering fire!

(In the background, an 'artillery cannon' fires a plasma mortar, which fires out overhead. The Master Chief moves along)

Marine #6 (O.S.): Grunts, down low.

Sergeant Banks: When I asked for reinforcements, I didn't think they'd send a Spartan.

(The 'artillery cannon' fires another mortar. This time, it hits a nearby building, destroying part of it and causing debris to fall)

Sergeant Banks: We gotta take that thing out. Cover me!

(Sergeant Banks walks over to a dead Marine, and takes out his radio)

Sergeant Banks (O.S): Tech Aids H.Q. This is Sergeant Banks. I got a hostile Artillery 200 meters east over my position. Bring smoke, over.

ODST (O.S.): Hostiles right.

(The Master Chief continues to fight, with the Artillery Cannon still intact)

Sergeant Banks (O.S.): Dammit, H.Q. is anybody on this freq!?

Major Easley (O.S.): Sergeant, this is Major Easley. Hang tight. We're inbound.

(Overhead, two Longswords approach the Artillery Cannon, and destroy it, then continue on)

Major Easley (O.S.): Verify delivery of ordnance on target.

Sergeant Banks (o.s): Dead on major! Target neutralized!

Sergeant Banks (to Master Chief): Take my weapon, you'll need it.

(He gives the Master Chief two SMG's)

(Master Chief jumps off the balcony, and into further battle. Later, he goes into the damaged building, where more 'Jackals' appear)

Marine #7 (O.S.): Frag and clear. Clear out.

(Later, the Chief exits the building and sees a group of jackals, which get run over by a Gauss Warthog)

Marine #8: Could use you on the gunner sir. We got your back.

(The Chief enters the gunner. A Shadow passes by, and he destroys it)

Marine #9: That's the way. Yeah!

(The Warthog goes along. Then, two 'Ghosts' appear)

Marine #8: That better buff out.

Marine #9: Ghosts! Making a break for it. Quick!

Marine #8: Don't worry. I got'em.

Marine #9: Do you wanna let me to drive?

(More Ghosts arrive)

Marine #9 That's one!

Marine #9 That's two! C'mon! Whose got more?

(A Phantom flies overhead)

Cortana: A Phantom!

Marine #8: Hang on!

(A second Phantom comes)

Cortana: Brutes!

Cortana: Look out!

(A Brute drops in from the Phantom. He kills both Marines, then knocks out the Chief, and the Warthog crashes into the wall. The Chief kills the Brute)

Cortana: Ghosts! To your right.

(A Ghost approaches)

Cortana: Wait for it...

(Master Chief hijacks the enemy Ghost)

Cortana: Nice!

Cortana: The Marines won't stand a chance if those Phantoms double back. See if you can draw them off.

(The Chief escapes)

(Fade to white)

(Cutscene)

(The Ghost zooms off, and the camera follows it. Behind it, a Phantom approaches, followed by a ghost, and another Phantom. The camera zooms in on the Master Chief. He looks back. The first Phantom starts shooting at the Chief with the frontal turret, with another ghost leading the Chief. He narrowly misses the shots of 'plasma'. The Phantom shoots at the 'Welcome to 'New Mombasa sign to stop the Chief. It ends up falling on the Phantom, and the Phantom flips on it's side and explodes, with the Chief escaping'')

Cortana: Chief...

Master Chief: Hang on!

(The Chief approaches a closing wall in the highway tunnel. He narrowly escapes, and scrapes the road behind him as he slides down the bridge)

(Inside the tunnel, an enemy Ghost piloted by a Brute crashes into the fully closed wall, and explodes. There are two explosions on the other side of the wall.)

Cortana: Bingo! There's the cruiser! Now all you have to do... is...

(Several Elites drop pods land around him. He turns around, and another drop pod lands in front of him. An Elite pops out. It activates its sword. Around it, more Elites activate their swords)

Cortana: Bet'cha can't stick it!

(The Chief activates his plasma grenade)

The Master Chief: You're on! (the Chief throws it)

(The demo ends)

Differences with the Final Game

 * The demo had a vastly different storyline from the final game. Much of it was rewritten to change the events.
 * In the final cutscene, John uses his right hand to throw the plasma grenade, but in all three games, he utilizes his left hand for the purpose of throwing grenades.
 * The New Mombasa Orbital Elevator is nowhere to be seen. Instead, a massive building made up of towering spires and complexes dominates New Mombasa's skies.
 * The Pelican Master Chief rides in is not destroyed, and instead lands normally and disperses its troops without issue.
 * Sergeant Banks is an injured Marine who gives Master Chief his SMG, introducing the dual wielding feature. He is directing an attack against a Covenant artillery cannon, instead of a Scarab.
 * Sergeant Banks is introduced at the beginning, instead of the end of Metropolis.
 * Sergeant Banks is Caucasian instead of African.
 * Brutes are attacking Earth side-by-side with the Elites.
 * The Brutes voices are deeper, much like an ape, than in the final game.
 * The Chief is trying to destroy one of many CCS-class Covenant battle cruisers, instead of a single Assault Carrier.
 * The Battle Rifle reloads like an Assault Rifle.
 * The Master Chief fires the SMG's at the same time, and he never reloads them.
 * When the Master Chief changes to the Battle Rifle from the SMG's, he doesn't drop the other SMG.
 * The Battle Rifle is semi-automatic, has no ammo counter, and is reminiscent of the way a paintball gun fires.
 * The Shadow's turret shoots green plasma blasts that look like charged plasma pistol shots, not purple shots. Also, it shoots more at a more regular pace, it doesn't get faster as it shoots, although this is the same in the final version when manned by Elites.
 * It is Cortana, not Lord Hood, who outlines the mission (defeat Covenant ground forces and destroy their cruiser, instead of infiltrating their carrier to capture the Prophet of Regret).
 * Only one Pelican, instead of three, heads to New Mombasa. Also, the In Amber Clad is not seen.
 * Major Easley does not appear in the final game.
 * The Elites you see are either some sort of Stealth Elites or a new Elite that didn't make it into the game.
 * The Brute Shot shoots like a large plasma projectile which flies straight instead of the frag grenade that falls and bounces after a few feet.
 * The Plasma Pistol shoots a larger bolt.
 * Grunts are seen driving Shadows.
 * The Phantoms have a different appearance and are destructible.
 * Brutes bleed purple, but in the final game, they bleed Blackish-blue.
 * The Fragmentation Grenades made the same type of explosion like they did in Halo: Combat Evolved, but are much weaker.
 * When a Brute jumped on top of Master Chief's Warthog, he knocked out two Marines instead of just one.
 * When Master Chief hijacked the Ghost, he stood on the ghost for a considerable amount of time before he kicked the driver out.
 * The Brutes are weaker than they are in the final game and were easily killed.
 * The Battle Rifle's melee attack shows three different animations at the same time instead of only one at a time--this was the first animation shown by Bungie of their proposed "melee combo" system, which was cut out of the final game due to time constraints.
 * When the Chief shoots a Phantom with a Gauss Cannon a green and blue plasma spark appears.
 * The Gauss Cannon has a faster rate of fire.
 * The Prophet of Regret does not lead the Covenant invasion force on Earth.
 * The back of the Phantom is open and the troops disperse like on a Pelican.
 * If one looks closely at the Elites' Energy Swords, they can tell that they have the same appearance as the Halo 3 ones, with the pointed edges around the hilt when turned on.
 * Jackal Shields are a bright fluorescent blue, instead of bluish-green in the final version.
 * The Jackal Shields appear to be a figure-8 shape, instead of the circular shape seen in the final game.
 * Jackals are also seen moving foward togather in a phalanx formation (as opposed to just running around normaly) shortly before being run over by Warthogs at 4:46.
 * The Ghost's fire mode is different to that of the final version. In the final version, the mode was alternating blasts from each Plasma Cannon. Here, it was more like Halo 1's fire which fired both Cannons at the same time. The rate of fire was also increased and the Plasma Bolts travel faster.
 * There is a huge increase in the number of Grunt death animations where they stop in their tracks when killed and slowly fall forward. Few of the killed Grunts in the trailer perform the classic "Grunty Death Backflip" when killed with Battle Rifle fire.

Trivia

 * The Halo 2 E3 Demo received an honorable mention on Gametrailers list of the Top 100 Trailers of All Time in 2011.