Assembly

Assembly (formerly known as Purple Reign and even previously known internally as Descent) is a Halo 3 multiplayer map which is part of the Mythic Map Pack which additionally includes Orbital, and Sandbox. It was originally planned to be in the Heroic Map Pack, then the Legendary Map Pack, but was replaced due to the fear that it wouldn't be finished on time. This map, Assembly along with Sandbox and Orbital was released February 27- March 3, 2009, depending on world region, with Halo Wars Limited Edition  LCE. It was released to the Xbox Live Marketplace on April 9th, 2009 with Sandbox and Orbital.

Design
The map is based inside a Covenant Scarab factory. When looking overhead, legless Scarabs can be seen moving by some kind of automated gravity beam. As such, the area outside the level is immense.

The map itself is bowl shaped, sloping toward the center. This bottom floor is dotted with pillars and walls for cover. It has an outer rim with four bridges, that connect to the two-story center structure, and has small structures on the rim intended as high ground. The bases are symmetrical, but the level actually has two distinct sides, with a lift on one side and what we refer to as the "dugout" on the other, making side differentiation that much better. Line of sight is generally open, with mid-range combat being optimal when on the second level. However, within the center structure and around the pillars that dot the bottom level, close combat is possible.

The map is focused on competitive playing, as it is a multi-story arena-style map. It features two "somewhat enclosed" bases, with one-way mirrors on the second floor (like those in interrogation rooms), where players will be able to look out, but players outside will be unable to see in.

Mystery
Before Assembly was removed from the Legendary Map Pack, it was stated that one of the maps would expand upon the Scarab-Hunter mystery. In a recent Weekly Update, it was stated that, "One base of this open-air arena could end up getting called 'Energy side' and another call-out could end up 'Hunter side'", so it's possible that this was the map they were referring to. The two sides are named as such as one side has tubes containing hunter worms and the other contains electrical cables. The tubes presumably are fed into the scarabs, filling the empty husks with the two.

Adding to this mystery, Luke Smith posted on a thread on the Bungie forums that "the name Assembly is extremely appropriate." It would be found that this comment, came after the release of the name of the map in the Weekly Update on the same day. His comment would refer the fact that Scarabs are assembled within the facility. The Scarabs are carried along an assembly line, with the playable area of the map being one of the machines that constructs the Scarabs.

It was revealed that like the Hunters are made of many Lekgolo Worms joined together, a Scarab tank is a whole colony joined together.

Assembly Line
As is obvious from the level's name and enviroment, the level takes place on a facility as part of a massive scarab production line.

Above one's head is a large gravity line-type conveyor belt, which transports husks of Scarab Torsos, without inner workings, legs, or armaments. The husks still appear energized.

The husks come out of a large orange hole of some kind on one end of the map, with the movement of machinery and releasing of steam. When the device halts above the facility the players play upon, which has a large energy beam that leads up to a large ring around the husk. The exact function is unknown, but the device gives off a large electric field and the husk shakes wildly.

The husks then continue along their way in the same manner as they came into vision, though entering a blue hole, once again with machinery and steam releases.

The production line appears to take place in a lake of green, or something of the light. This is possibly water appearing green in the poor lighting, used to power the machinery, possibly with a hydro processing plant somewhere out of vision. It is also possible that it is a large basin of coolant (like the green liquid dripping from the large holes in the Truth and Reconciliation on Installation 04) used in the production machinery, and possibly in the scarabs themselves (As in Halo 2 when the Scarab's main gun drips a green liquid when firing).

The station the player plays on appears to be like an island, isolated, with several devices appearing to repeat covenant numericals. It possibly processes the lake for energy, as it has a large energy beam running through the center shaft.

It is not known what the seen process or machinery does or is used for, and nothing is known about the process other than what is seen.

Skull
The crest of the hidden Skull on this map appears to be what looks like that of the Lekgolo worms referring to the Scarab assembly line in the distance.

Trivia

 * In the images, fog can be seen in the distance if you are far enough away from a structure. Similar fog can be seen on the Halo 2 level High Charity near in the parts with Flood though with likely different origins from one another.
 * The map may have been after the Flood took High Charity, but it does not show that the Flood took over this place.
 * The codename name of the map, Purple Reign, could have been a homonym with the TNT firework "Purple Rain", or it could also be linked as a tongue in cheek reference to the song "Purple Rain" from the artist Prince.
 * Although not a true screen shot, a pen rendering of the map was featured in the Bungie Weekly Update on July 25, 2008.
 * A Bungie Weekly Update has released several screenshots for those who are unable to reach PAX 2008.
 * You can get the Hammer Time Achievement for getting 5 Hammer kills on this map.
 * It has been confirmed by Game Informer that the pilots of the Scarabs are the Lekgolo worms which make up the Hunters.
 * In one of the bases, individual Lekgolo worms can be seen in tubes filled with a yellow liquid.
 * The blue lines beneath where the Gravity Hammer spawns appear to make up the Marathon symbol. Also, another Marathon symbol appears in the blue lines inside the tubes at the top of either base.
 * Assembly currently is the map with the smallest play area in Halo 3, despite it being labeled as for "2-8 players".
 * If you overload this map the skull will disapear and the grav lifts will stop working, but the animation for the rocket tower is still there.
 * Assembly is one of the three maps in the Halo Trilogy to not have a sniper of any sort or a Shotgun.