Halo trailers have usually fallen into one of three categories: announcement, multiplayer, and campaign. Of these, announcement and multiplayer trailers are usually very straightforward, so here I'll be focusing mostly on the campaign trailers.

A Seamless World

The announcement trailer for Halo 1, shown at MacWorld New York in 1999, was ostensibly for a third-person action title, and purported to integrate examples of what gameplay would be like with a basic narrative: a lone soldier lures aggressive aliens into an ambush set by his buddies; they lead the aliens on a cross-country vehicle chase, and finally confront another alien and steal his air vehicle. There was no dialogue, but we were given a taste of what the environments and vehicles were expected to look like, and the kinds of gameplay situations the player might find themselves in. The polish of the graphics and the variety of gameplay immediately generated a lot of interest.

The Drop Zone Is Clear

The campaign trailer for Halo 1, shown at E3 in 2000, took that early trend even further; it was essentially a short film-- a combination of the scenes that would come to be called Halo's cinematics, filmed from a perspective appropriate for showing the action and plot elements the studio wanted to get across, and gameplay sequences, filmed from a third person perspective (the shift to a first person shooter had not yet become public knowledge at that time).

We're given recognizable and distinct UNSC marine characters (voiced by Bungie developers) who investigate a structure on Halo only to be ambushed by the Covenant who have gotten there first. In their attempt to escape several are killed and a few Covenant vehicles are destroyed. In the nick of time, the Master Chief lopes over the horizon with a plasma sword to save the day, cutting down the Elite who just informed humanity that their destruction is the will of the gods.

Again, we've got a video that shows items integrated that the Halo games themselves present separately: the advancement of the story through cinematics and the interaction between actors through gameplay.

Hope Springs Eternal

Although the scenario in the E3 2000 video survived (mostly) in the Silent Cartographer level, many elements were lost. Marines don't follow you into the underground structures; there are no Covenant vehicles save dropships in that encounter; the ambient life, blind wolves and dinosaurs, are not in the game at all; and since Elites don't speak English in Halo 1 there's no one to deliver the line about our destruction being the will of the gods; the plasma sword was not usable in Halo 1.

In short, while a very enjoyable piece of electronic entertainment in its own right, with a stirring score, impressive visuals, and charismatic characters, the E3 20000 video set up expectations that the game did not-- and some might argue could not-- hope to meet, in part because of elements that were altered or discarded during the development process, and in part because of the approach that assembled gameplay-like events into a strict narrative drama in a way that would be near impossible to replicate during actual play.

What If You Miss?

While shorter, the Halo 2 Announcement Trailer also fits generally within this trend; however, the scenario altered from what looked like the arrival of a lone Master Chief on an abandoned space station and hurling himself out an open airlock, presumably to free fall onto the exterior of a Covenant cruiser and attack it from within.

When the game shipped, that scene was actually quite different. After defending a populated space station and defusing a Covenant bomb, the Chief hurls himself out an open airlock with the bomb in order to use it to blow up one of the Covenant's orbiting cruisers.

There were likely compelling gameplay reasons for making this change. After all, Halo 1 had just presented the player with two levels that take place on a Covenant cruiser: to do another early in Halo 2 would pose problems. If the environments were consistent with the earlier game, it's likely that players would be bored. If they were changed significantly, they would wonder how Covenant ship design was able to change so much in such a short time. It would likely have been a no-win situation. Instead, the Covenant architecture levels were shifted to High Charity, and the announcement trailer became the cutscene that ends the first level, Cairo Station.

We're Going In

With the E3 2003 Halo 2 Demo, the trend of marrying gameplay mechanics with plot advancement within a cinematic structure reached its zenith. The Master Chief drops into New Mombassa on a Pelican with Sergeant Johnson (revealed for the first time in this video as being alive after Halo 1) to provide relief for marines holding down a Covenant artillery emplacement. We see the UNSC chain of command crippled as the ranking officer was killed shortly after insertion; we meet Sergeant Banks, who shows us how to dual wield; we meet the new jackals and grunts and try out the Battle Rifle; get a taste of manning a Warthog's LAAG cannon while marines drive for us; see the Brutes for the first time and watch as they board the Warthog; get a chance to board a vehicle ourselves and use it to escape; and finally see the Chief and Cortana put into a typically impossible situation and the Chief cope with a typical one-liner.

With an even more impressive musical score and impressive visuals, this demonstration was also a fine dramatic short film. What was even more impressive about it was the fact that it was not prerendered; at E3, Bungie employees had to control the action of the Chief and perform a sequence of nearly identical actions in order to keep the scripted encounters working properly. Failure to execute those maneuvers would result in the demo going off the rails. The fact that this was sometimes difficult was perhaps an indication of the coming controversy.

Bet You Can't Stick It

Players who watched that video expected to be able to play that scenario. But it was not to be. The level geometry itself was almost completely discarded before the game shipped. The sequence of events was altered, and spread out over two levels-- Outskirts and Metropolis. Certain behaviors were removed: Jackals never advance in a wing formation as they do in the video, and neither of those levels contain Brutes. While you can have marines drive in Halo 2 while you gun, the result is very rarely as satisfying and dramatic as it is in this video. Marine drivers often get hung up on obstacles, collide with objects and other vehicles, seemingly intentionally, and generally drive much more slowly than the player would himself. The peaceful Pelican landing that serves to build dramatic tension at the start of the video becomes a crash landing at the start of Outskirts (can any UNSC pilot keep these things in the air besides Foe Hammer?) and the Elites surrounding the Chief at the end of the video survives only as an ambush by landing pods near the end of Outskirts before entering the highway tunnel that leads to Metropolis-- and that only happens on Legendary. The vehicular combat was shifted to the end of Metropolis; but while it was easy not to notice during the demo video that the Warthog was driving around on a small, closed loop, during actual gameplay it was impossible not to notice.

Players expecting to be able to play through that exact scenario, or a scenario that delivered cinematic drama and entertaining gameplay simultaneously on that high of a level were bound to be disappointed, and many were; not necessarily because the game failed to deliver solid gampelay value as well as entertaining narrative, but because in the actual game these elements are, more often than not, presented separately rather than together.

Defying Gods And Demons

Whether because Bungie recognized that trend could not continue, or simply could not dedicate the same amount of resources to producing the trailers for Halo 3, we've seen a marked change in the nature of the trailers shown for the latest Halo title.

Halo 3's announcement trailer provides mostly atmosphere, not gameplay. We see vehicles, but they are not engaged in combat. We see the Chief, but all he's doing is walking towards the camera and peering out over a cliff. We're given the tiniest hint of story: there's something big under the African sands; the Covenant are digging it up and turning it on.

There are no gameplay expectations built by this trailer. Since the events themselves (Cortana's in trouble, Covenant find Big Thing) are already foreshadowed by the end of Halo 2, Bungie could choose to include this cinematic almost verbatim within the game or not with little or no impact.

Likewise, the campaign trailer for Halo 3 released earlier this week shows cinematic and gameplay elements, but presents them in the form of a musical montage, rather than as an integrated dramatic play experience. As such, the gameplay expectations it sets up are rather modest: we see the Chief attacking Brutes with various weapons and vehicles, and a series of cutscenes that provide suggestions of what will go on during Halo 3. There's no single comprehensive dramatic gameplay experience presented here; Bungie could, if needed, change or remove many of the elements shown within that trailer without dashing players' hopes-- not that this would be done at such a late date; but I think the potential problem of having players say "but I want to play the level like in the video" has been eliminated with these two new trailers because of the way they were presented.