Backwash

Backwash is a multiplayer map featured in Halo 2. It was added to Halo 2 as part of the Maptacular Pack.

Summary
Backwash is a midsized multiplayer level in Halo 2, akin to the campaign level on Halo: Combat Evolved called 343 Guilty Spark. It is a large swamp set on Delta Halo. You can tell it is Delta Halo, not Alpha Halo, as 2401 Penitent Tangent can be seen floating around and humming to himself, and the architecture of the buildings differs from that of Alpha Halo. It is actually stated by the developers of Halo 2 that Backwash was originally set on Alpha Halo and based directly on the Halo: Combat Evolved campaign level,"343 Guilty Spark". It is also stated that they originally had 343 Guilty Spark floating around but decided to change him to 2401 Penitent Tangent because Spark's blue glow could too easily be mistaken for a Plasma Grenade flying through the air.

Matchmaking Removal
Backwash was removed from Halo 2 Matchmaking in the April 2006 Matchmaking Playlist Update (NOTE: Not an Auto-Update), due to problems with the Xbox 360 loading the fog covering the map. To this day Backwash remains the only map to ever be removed from Halo 2 Matchmaking.

Hidden Message
There is a way to get out of the level, but it requires super-jumping or a Spectre. With a person, get the him/her to Superjump over the invisible wall on the hill, then get them to stand on top of the base (red or blue). Get them as close as possible to the wall and then sword cancel up onto a small spot on top of the base. You can now sword cancel (try it a lot) through the wall. Then, walk through something that looks like a large amount of roots (surrounds the outside) and look for edge of the level. Then walk around until you find red ground. The message is very large, written in blood, and says: Looking a little rough out here. (Possibly because of the mold, fog, etc.)

To do it with the Spectre, go to blue base and jump on a small ledge that is right next to the invisible wall. Have the driver put on a severe handicap (if you don't have an overshield) then ram into you. If done correctly you will be smashed through the invisible wall.

Trivia

 * Bungie actually considered implementing 343 Guilty Spark over 2401 Penitent Tangent at first, but discarded the idea because of 343 Guilty Spark's resonanting blue-color. The Monitor's color would resemble a Plasma Grenade from afar. In the end it was ultimately decided that the red-colored 2401 Penitent Tangent would be in the map.
 * Telephone ringing can be heard in the distance.
 * Although the Monitor seen on this map was changed from 343 Guilty Spark to 2401 Penitent Tangent, the sound files used are still Guilty Spark's. Although they sound similar, the voice actors were different.
 * This map is obviously based off of the final portion of 343 Guilty Spark, a level in Halo: Combat Evolved.
 * Related to 343 Guilty Spark, Flood gurgles can be heard about. An easy way to hear them is to go into the bases ( small buildings on the sides of the map ) and turn the volume up.
 * Backwash in considered by some, the most un-popular map in Halo 2.

Easter Egg
On the main tower, use a Beam Rifle or Sniper Rifle and scope in on the tower from left of the Energy Sword. There should be a hidden gargoyle on the tower.