Avalanche

Avalanche is a large, symmetrical multiplayer map featured in Halo 3. It is featured as one of the three maps in the Legendary Map Pack that was made available on April 15, 2008.

Design
Avalanche is a large Forerunner power station set on the front of a huge glacial shelf on the new Installation 04. The structure pulls its power out of the densely compacted glacial ice that constantly builds up behind the station before it cascades into the ocean below it.

This map is a re-imagination, and, some would say, the successor of the map Sidewinder, from Halo: Combat Evolved. As the original Sidewinder featured elements that created slower gameplay, Avalanche was Bungie's chance to start over again. Certain obvious design elements have been removed due to their slowing effect on multiplayer, such as the tunnel in between the two bases, while at the same time adding new ones, such as the many Man Cannons. The Man Cannons located in Avalanche are much more powerful than those located in other Halo maps, being able to launch players halfway across this huge map.

The map itself is centered around two bases at each end of a U-shaped snowy valley. One side is noticeably lighter than the other with trees and bare rocky walls, and the other is much darker with more shadows, no trees, and icy walls. To add an interesting dynamic in one-sided objective games, there's an asymmetry in vehicles; the assaulting team has exclusive snow-camo UNSC vehicles at their disposal, while the defending team has ordinary Covenant vehicles to begin with. The map is set to prefer objective gametypes, but works well with BTB slayer and snipers as well.

New Forge objects have been created just for this map, which can dramatically alter gameplay. These objects include energy blockers to restrict access to entrances and exits, large watchtower bases, and Forerunner ramps among other common objects which can be used to make an entirely new base, if you are creative enough to do so. Map effects have been added to the Forge palette, called Forge Filters. These items are found in the other two Legendary Map Pack maps, Cold Storage and the Mythic Map Pack.

Gameplay Features And Changes

 * A number of man cannons and a large cavern area have been added.
 * The Forerunner structures serves as giant man cannons, and can launch players halfway across the map.
 * In one-sided objective gametypes, the attacking team has UNSC Vehicles, while the defenders have Covenant and Loyalist vehicles.
 * All UNSC vehicles now feature snow camouflage colors instead of the traditional green UNSC color scheme.
 * The Scorpion Tank, is only available to the assaulting team on one-sided objective based games; during team slayer, neutral and multi objective games both sides will have the Wraith Tank.
 * A bottomless pit is located in the center infantry area of the map. Using the man cannons there can get you across this pit.
 * Energy doors can now be placed in Forge to cover up exits.
 * Forge Filters can be placed on Forge games to change the visual feel of the map.
 * Transport Hornets are added; Hornets that are not armed with the missile launchers.

Avalanche is an almost symmetrical map, with the only differences being the placement of rocks, and a small bridge leading to a small shelf in the canyon, minus the bridge the shelf is almost identical on the other side. There is a mountain that separates the two bases, but there is a path though the mountain creating a T-shape in the U, about mid way though the map there is a tunnel in the upper part of the map that connects the two sides, from that cavern there is a man cannon leading to a lower level that has an exit at the crest of the U. There are Man Cannons placed about the map in such a way that a foot soldier can move throughout the map at a fast pace, though vehicles are still the main choice of transport.

Avalanche Heavy
Soon after the release of the Legendary Map Pack, a variant was introduced to Big Team Battle called Avalanche Heavy. This variant of Avalanche mirrors Sidewinder in many ways by adding scorpions at both bases and adding teleporters in the middle (the U-Bend specifically), along with additional vehicles and weapons, such as a Spartan Laser within each base. Avalanche Heavy can be downloaded here.

Strategies

 * The best possible defense strategy is to grab both the M41 SSR MAV/AW Rocket Launcher and Turret and bring it back to the base; however, remember that no man can defend the base on his own.
 * If you are on the assaulting team, grab the Shotgun, a BR55HB SR Battle Rifle or a Sniper Rifle System 99D-S2 AM and take out those with the heavy weapons attempting to gun down your team's vehicles. You can close in with the Shotgun or snipe from afar with your scoped weapon. Be careful to remember to watch out for incoming rockets, lasers and, counter-sniper fire.
 * Take the Laser and stay around the other side's camo area (pick it up if it's there) and try to take out the opposing teams vehicles. Once those are gone, take the Ghost and capitalize on the fact that there's close to nothing on the map for the next minute and a half that will be able to destroy you.
 * When planning to enter the teleporter to capture the flag, detach the nearby turret or grab the rockets, and stay near the teleporter. If a teammate is killed whilst trying to retrieve the flag, the enemy will likely investigate by going through, thus giving you the chance to obliterate them.
 * If you have the flag and have enemies chasing you, go through the teleporter and stay to one side. When your enemies come through give them a bone cracking melee, it is an easy way to defend the flag until a teammate can return you to the base.
 * If a tank is harassing your base, just sneak up on it from behind. If you use active camouflage, the driver probably won't even know that you jumped on.
 * In any objective gametype that involves the Scorpion Tank, it is imperative to remember that the best way to keep it from being destroyed is to stay as far away from an enemy stronghold as possible, this will lessen the chance of the tank being hijacked or destroyed by anti-armor weapons.
 * When on a CTF game, try stealing the enemy's newly spawned Hornet or Warthog and meet the carrier at the teleporter.
 * A good way to capture the flag or plant a bomb, is to grab a Warthog or a Hornet with two other friends. Make sure someone has a shotgun. Drive or fly to the invisibility an have one grab it too, then head for the enemies teleporter to their base. Park the Warthog or Hornet inside the small teleporter room for a quick getaway latter and grab the Rocket Launcher. With these weapons grabbing the flag or bombing the base should be easy. Go back though the portal with the flag, get into the getaway vehicle, and go to your base's teleporter room to score quickly (or to grab the bomb again), repeat for as may times as you can get away with it.
 * A unknown but effective sniping spot is next to the trees on the other side of the Ghost, you can snipe anyone that takes the mancannon to get the Trip Mine, Ghost or Laser.
 * The toned-down Hornet is not a very good offensive platform on its own, quickly being dealt with by other vehicles like Banshee or Warthog turrets. Use it to quickly transport team-mates or quickly defend your base. If you do want to assault the opposing team's base, have a team-mate use the Wraith for ground control. Your enemy will have to decide which target to focus on first, allowing the other to effectively take the threat out. A Scorpion can make short work of a Hornet.
 * Although the Hornet has been toned-down, it can still be invaluable in CTF and Assault games as the transport for the Objective carriers, because it is actually faster than the Standard Hornet. As such, use the Hornet as a Support vehicle; Provide some firepower support on enemies and try to keep the vehicle alive.
 * When fighting a hornet in another vehicle keep it moving backwards into a wall or a tree, this way it can be dealt with easily.
 * Because of how the Hornet moves, it is very easy to force a Hornet pilot to bump into a tree or wall, causing the Hornet to lose control temporarily. This is a great time to strike, as the guns on a Hornet do not rotate.
 * When going through the central cave, watch out for anyone opposite the Man Cannon pathway, as many players like to jump up the sloped wall and camp there with a Shotgun to quickly eliminate anyone who passes by.
 * The Spartan Laser can also be positioned here to help take out large vehicles, controlling this area with Sniper and Laser can contribute dramatically to your team's efforts in objective games, damage-wise, or just warnings for your team-mates.
 * The Hornet is extremely vulnerable to the Spartan Laser. Control of the air is determined by control of the laser.
 * An effective trap to make is to slip a trip mine on the teleporter in your base. Be sure to warn your teammates or you could be kicked from the game.
 * When on the Attacking team in One-sided objective games, have the Scorpion go ahead of the team and attack first to eliminate the bulk of the enemies' defenses. Then it is safe for other vehicles to take care of any stragglers.
 * If you get the bomb, take the shield and active camo and proceed to the enemy's base. Since you have the camo, nobody can see you. Plus with the bomb, you can easily take out any defenders with the bomb's impressive one hit kill.
 * If you get the flag and your team is nowhere to be found, you will have to score it on foot. The best way to do this is to take the teleporter out of the base, go off the Man cannon beside the rockets, go into the ice cave entrance, go off the man cannon in the cave, and go to the direction of your base, go on the little walkway to your base and score.
 * A good tactic for assaulting a base is to use "Paratroopers". To do this, pilot a Hornet, and get some passengers that have close ranged weapons (most preferably a shotgun), then fly them overhead of the base and drop them down. They will be very unexpected unless any enemies spot the Hornet. Also, try getting a Paratrooper to use an active camo for increased effectiveness.
 * Often at the start of the game, the pilots of both Hornets will have a "Hornet duel" blasting each other with their weakened machine guns. Often one of the two will retreat, if it does this then fly up to the beam and get as close to it as possible. The enemy pilot will think you retreated and advance on your base, if it does this strike. The only flaw in this tactic is that any player that looks up and can easily kill you with a laser.
 * If you don't want any enemies to sneak in your base through the teleporter, drive a Mongoose into your base and block the teleporter with it.
 * A fun and bold tactic is to charge up the mancannon with the fully armed warthog to splatter and shoot anyone defending to death, the passenger can grab the flag and you can easily escape by hitting the reverse.
 * You can slip a Trip Mine under enemy vehicles. In objective-based games such as Capture The Flag and Assault the enemy will no doubt grab a vehicle. You can take advantage of this to wipe out multiple players. Another tactic is when you see enemies charging towards your base to grab the Flag or plant a bomb, plant the Trip Mine at that spot. The Mine will either wipe out an enemy or two's shields entirely or may kill them.
 * The Mancannons are useful as an attack strategy, instead of a movement one. Throwing grenades (Frag grenades work the best, then spike grenades, and then Incendiary grenades, although the latter has to be edited onto the map with Forge. Plasma grenades are the least effective due to their low area of effect) into the cannon can toss it halfway past the map, or throwing them into the cannons near the bases is a good base assault tactic. Trip mines are best there as if you are fighting someone on the Mancannon, and have a trip mine in the base, you can force them into the cannon, and then toss a grenade into the cannon. This has a good chance of an easy kill.

Trivia

 * During production, Avalanche's code-name was Cottonball. Most likely because of its color and relation to snow.
 * If you look at some of the ice pillars around the map you can notice steam leaving leading many to believe that there is something beneath Avalanche that needed the cold around it to keep it hidden, such as a factory.
 * Avalanche contains the most vehicles of any Halo 3 multiplayer level, even more than the number on Sandtrap (excluding Elephants). It is also slightly larger than Sandtrap.
 * The vehicles with snow camouflage are the Hornet, the Warthog, the Mongoose, and the Scorpion.
 * Many design elements of the map seem to have been drawn from the Halo 2 map Containment, such as the new design of the bases.
 * The Hornets in this map are identical to the Transport Hornets on Sandbox.
 * G4-TV held a promotional contest named the Sarkatholon on this map for the winner to receive the Recon armor permutation.
 * The Avalanche Vacation can be done on this level.
 * The description states that it has "Ancient battle scars". This is unlikely, as it is a brand new Halo.
 * It was remade as Diamondback in Halo Online.