Construct

Construct is a Halo 3 multiplayer map that takes place at one of the Ark's "spokes".

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

Layout
The map is Forerunner in nature, set similarly to the Cartographer on The Ark. Overlooking a giant ocean and a 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. Also two ramps extending up to hold the sword arm can be used to gain access to the upper level. 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 Drain upon entrance to the yellow grav 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 these 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 the "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.

Note: An alternate route to the Energy Sword is a long narrow sloped ramp (which is quite possibly a support strut) next to both of the purple lifts on this section of Construct, it leads to the sides of the ramp that leads to the large walkway that leads to the Sword.

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 supply of weapons is located here, and third, the 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. This is by far the most sought after position in the entire level. The purple lifts provide two ways to assault the yellow lift zone from either side but it is possible to defend this zone if the players stick one or both of the two following areas:
 * The "angled" hallway to the right (if you are looking at the yellow lift) of the lift. Though people watch for defenders in this hallway the defender often has the advantage because he sits stationary waiting for an attacker to come into view while the attacker must be ready to train their sights on the defender when it slips into view.
 * The overhang over the ramp to the left (if you are looking at the yellow lift) of the lift. You can cover both the ramp leading up, as well one of the purple lift zones from this position. If you start taking heavy fire just put the semi-transparent wall in between you and the attacker.

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. One way of doing this is to throw grenades up the lift before entering it, to kill or weaken any enemies camping at the top.

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 Drain 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 support struts that allow climbing up and down. At the opposite end of this walkway, players can find the Sniper Rifle (upper portion), and a Bubble Shield (lower portion). In the middle area, a player can get a Brute Shot and shoot up the wall and get on top of the arch way towards the plasmas and Sniper Rifle. This is a good idea if you have the sniper with you.

Trivia

 * Players can easily fall off the lower level onto some lower beams below. This can be especially useful in games such as Oddball, Juggernaut and Infection as it is extremely difficult for the opposing force to reach you. You can only exit this space via dying, this is possible by repeatedly jumping until the "you fell to your death" notice appears. (This glitch has been changed in the matchmaking variant of Construct.)
 * 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 ( it is the only map in matchmaking that you can get the Incineration medal).
 * If you put in a Banshee on Forge you can fly onto one of the 'arms' where you could place spawn points and teleporters. The Sentinels fly about five meters past the instant kill wall or the "kill zone" in other words.
 * If you fall off Construct and press Y in theater mode you will see that the water from the falls comes right up to the level but is invisible due to fog/watery mist.
 * If you get in a Hornet or Banshee and you fly too high you will be killed and fall to your death.
 * This is the only map in Halo 3 that does not spawn a Shotgun by default.
 * It is possible to reach the normally inaccessible framework below the lower level by overloading the map and crouching through the mesh under the purple gravity lifts. After this has been achieved it is now possible to set up Teleporters to get in and out freely. Although it is possible without overloading by forcing downwards on the purple lifts in forge mode then turning back into a spartan.
 * It is also possible to get out onto the large "girders" that stick out into the open, outside the normal boundaries, by overloading the map. Also overloading is not needed for all the girders.
 * A teleporter was originally planned out for this map as seen in the map's image provided for Matchmaking.
 * Construct is considered one of the most popular Halo 3 maps in MLG. Most likely the reason is because of the numerous amount of Battle Rifle spawn points and the wide-open places where BR headshots are always abound.
 * This is the only map where you can spawn 4 Hornets, which is more then the usual 2.

Strategies

 * If you are behind the orange lift, you can throw grenades at the wall ahead and they can bounce up to the higher level, where some players may be camping the lift. This is good if they are out of the lift's landing zone, avoiding grenades coming up the lift.
 * A Power Drain is present on the bottom most floor in front of the Yellow lift, as well as one near the Energy Sword spawn. These coupled with grenades can be useful to throw into the lifts. It is important not to follow the power drain up too quickly as it will destroy your shield as well. Most opponents avoid standing in the area that would be affected by preemptive strikes with grenades or power drains
 * It is possible to throw Frag Grenades from the lower levels on the sloped ceiling leading from the left purple lift to the orange lift, where the Hill is, this can be used to clear out the Hill one way or another.
 * Remember that power cores can be pushed up the purple lifts, and along with a tossed grenade, make it easier to soften and/or clear out enemies camping at these lifts.
 * When trying to clear out the orange lift from the purple lifts, using frag grenades in conjunction with the angles of the walls can make this easier to achieve.
 * The two metal beams which extend diagonally from the middle level to support the far end of the top floor are actually walkable and provide an excellent shortcut to the Energy Sword.
 * If you throw a Power Drain up the gravity lifts you can drain or partially drain any campers shields.

Forge

 * Using two way teleporters, you can create a random network of teleporters, all you need to do is set more than two of the two way teleporters on the same channel, this creates a random teleport, and placing one or two on each level of Construct allows for easy getaways.

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. Hiding spots such as the one below the level near the orange lift have been removed, due to an invisible slant than would force the player to slide off and fall to their death. Another spot that has been removed is the spot behind the glass. When you try to jump onto the ledge, an invisible barrier blocks you from entering, causing you to fall to the lower levels.