Construct

Discovery
"Construct" is a map referenced in the Halo 3 Beta code. It was then confirmed in a leaked photo, and then explored in two videos.

Layout
The map is Forerunner in nature, set similarly to the Cartographer on The Ark. Overlooking a giant ocean and beautiful waterfall, this level may appear symmetrical, but on closer inspection is really asymmetrical in nature. Construct has three distinct levels, each connected by a series of ramps and gravity lifts. As a result of its unique nature, Construct has a variety of weapons and equipment. The upper level can be reached by the "main" or "yellow" gravity lift at the far side of the level (opposite the ocean). Rather than take the "main" lift, players can travel up one of two smaller, "purple" lifts. A long, narrow channel stretches out overlooking the vast ocean below, and the main level of the construct.

Lower Level
The lowest level of Construct is split into 2 sections, that are similar in shape to a plus (+) sign. The main corridor leads to the middle level at one end, and the yellow gravity lift at the other. Players can find a Power Drainer upon entrance to the yellow gravity lift. The smaller corridor intersects the main corridor at its center, and offers a ramp (one on each side), up to the middle level. A Spartan Laser and Missile Pod exist on each side of the small corridor on the ramps leading to the middle level.

A Flamethrower is present at this intersection. A small, c-shaped hallway connects the main corridor to the smaller corridor, which goes behind the purple gravity lifts. A Mauler can be found in each of these small hallways. Players also have the ability of reaching the top level via the yellow and purple gravity lifts from this low level.

Middle Level
The middle level is almost synchronous with the lowest level due to the ramps connecting the two levels. A portion of the middle level has been removed, offering a quick drop into the lowest level if a player chooses to not use the ramps. Players can also access the yellow and purple gravity lifts from this level of the map as well. This is the highest level of the map where the gravity lifts can be used, as they only travel upwards.

This level of the map can often see fighting, but is is mainly used as "transport" level, getting players to their destination quicker. Players can also choose a slower, and possibly safer route than the gravity lifts by traveling up the ramps. The main ramps circle around the yellow gravity lift, and lead all the way to the top level. The map's only Brute Shot exists on these ramps.

Upper Level
Remarkably, this area of the map sees practically all the action that takes place. This is for several reasons: first, there is little to no areas for cover on the lower levels, second, nearly the entire level's supply of weapons is located here, and third, the level's three power lifts lead to here and it is often of good strategy to camp at the top of these lifts in hopes of killing a player as he comes up it (in such a situation the player already there has a distinct advantage over the player coming up the lift). There are three main areas of the upper level as well. The "yellow lift zone" contains the area where players exit the yellow gravity lift, as well as the paths leading to the purple lift zones. The second zone on the upper level are the "purple lift zones," which occur at two ends of the top level. The final aspect of the upper level is the long walkway extending into and outside the main parts of the map, containing the sniper rifle at one end and the Energy Sword on the other.

Yellow Lift Zone
In this zone, players can trap the opposing team from entering the top level of the structure via the yellow gravity lift or the ramps. It is often the object of much fighting as one team tries to storm the upper level, while the other team attempts to hold them off. A good tactic for those traveling up the lift is to destroy the fusion cores that are on the walls of each side of the yellow zone. On the left of players, as they're looking into the lift, are the ramps that lead up to the top level from the bottom.

Purple Lift Zones
Players can rapidly travel up to the top level via one of the two purple lifts. These zones can also be a death-trap for players traveling up them. A helpful trick is to toss grenades up the lifts, hopefully softening the players, and then traveling up to kill them. Other than the ramps, this is the only way to reach this section of the top level. Despite being a heavily contested area, if player can effectively coordinate an assault, they can take the upper level with minimal casualties.

Narrow Walkway
This narrow walkway extends out over the level looking out into the vast ocean below, and has two levels. Players can find a Energy Sword and Power Drainer at one end of this walkway. Players can easily access the middle or lower levels of the map by jumping from the edge of this walkway. There are two very narrow ramps that allow climbing up and down. At the opposite end of this walkway, players can find the SRS99D-S2 AM Sniper Rifle (upper portion), and a Bubble Shield (lower portion).

Trivia

 * Sentinels and Constructors float out far from the level, but can be destroyed with long range weapons.
 * Construct is currently the only map that features a Flamethrower by default.
 * A popular strategy on this map is to camp at the top of the level with the Energy Sword, Mauler, or Flamethrower. Conversely, if at the bottom of the level, it is common to throw grenades and / or equipment or push nearby fusion cores up the purple lifts.

Matchmaking Adjustments
For reasons not yet disclosed by Bungie, this map has been slightly altered when playing in Matchmaking playlists.

As of the December 11, 2007 update, the Maulers that spawned at the top of the purple lifts have been removed.

It is believed that this change was caused by near-constant complaints regarding the large number of Maulers in many levels combined with the Mauler's ability to nearly-instantly kill an opponent at very close range. Many people felt that the weapon was unbalanced because of the close-quarters prowess of the Mauler, especially in CQB-style levels; this is a misconception.

The problem was a combination of the somewhat large number of Mauler spawn locations, the fast respawn time on a lethal close-combat weapon (usually only 45 seconds), and players not changing their play style to compensate for a number of camping and / or charging Mauler wielders.