Snowbound

Snowbound is a medium-sized multiplayer map in Halo 3. From Bungie Q&A on a Weekly Update, they hinted that it may take place on a former Forerunner planet near Earth, though it is currently occupied and being excavated by the Covenant.

Overview
Snowbound is a medium-sized, semi-symmetrical map set in a snowy Forerunner area with two large Covenant bases at either end of the map. The bases, known as high base and low base, are connected by an underground tunnel network. Much fighting takes place in or around the shield doors found inside the bases.

Rocky outcroppings are located along the southern and western edges of the map (Rock Side); Covenant-built Automated Turrets prevent players from exiting the map via its otherwise-unblocked northern and eastern edges (Tundra Side). When players venture too close to the map's boundaries, an alarm sounds, warning them to return to the bases before the turrets open fire.

In Bungie's 8/22/08 Weekly Update, Bungie announced the release of Boundless, a version of Snowbound that lacks shield doors (except the four which can be accessed on top middle) and has a slightly different weapon layout.

Low Base
Low Base is one of the two Covenant bases on the map. This base, which is located on the eastern side of the map, appears to be fully functional, though it has apparently been abandoned. It is often referred to by players as "BR Spawn" because of the two Battle Rifles that spawn on its outer rear walls. Inside the base, there is a Spartan Laser, two Spikers, and a Bubble Shield. Outside the base, a Carbine, a Spiker, and a Mauler spawn to the south; an Active Camo spawns towards the north. On top of the base, there is a Needler and a pair of Plasma Grenades.

High Base
Directly adjacent to Low Base, High Base offers a different set of weapons. High Base's lights flicker and buzz, implying that it has become damaged. The large sphere in the center of the base appears broken, and icicles hang from the base's exterior, implying that its heating system has stopped working. Whether this damage is the result of the base's abandonment or something else is unknown.

High Base is commonly referred to as "Sniper Spawn" or "Carbine Base" due to the Carbine and Beam Rifle it contains. Behind the base, players can find a Battle Rifle or a Plasma Rifle around the rocky terrain. A Mauler lies to the north of the base, and an Overshield to the south. Inside, there are two Plasma Rifles, a Beam Rifle, and a Power Drain. On top of the base, there is a Plasma Pistol and a pair of Plasma Grenades.

Outside Areas
The outdoor portion of the map is home to many predominant features, and is also a sniper's paradise.

Located between both bases, to the south, is the Underpass (or "Ghost Spawn"), a tunnel where a single Ghost (or Mongoose) spawns. In the center of the map, the Ice Cave Tunnel provides access to the Ice Cave, which in turn provides access to the interiors of both bases. A common tactic is to blindly toss grenades into the map's lower levels from this area, turning the underground corridors and tight spaces into grenade-powered deathtraps. Further to the north, on the opposite side end the Underpass, lies the Ice Cave's main entrance, with its distinctive overhang and large shield door.

Ice Cave
Predominantly known as the "Shotgun Spawn" in Lone Wolves or the "Sniper Spawn" in Team Slayer, heavy fighting occurs in this cold and icy cave. This area sees frequent carnage due to its high traffic, tight quarters, and position between the High and Low Bases. To the immediate south is a narrow, elevated opening with no shield (Ice Cave Tunnel). On the western side of the cave's interior is a tunnel to the High Base; opposite that is a tunnel to the Low Base. Directly north is the Main Entrance, which is protected by a larger shield door.

Entering the Ice Cave from the Bases or the Ice Cave Tunnel is extremely risky. The main entrance is very defensible, as it affords the player with a full view of the cave's three most-used entrances and its shield door provides protection. Above the Ice Cave's main entrance spawns a Brute Shot (top), as well as a Spiker to the west and a Mauler to the east. An often seen tactic on this map is to hide on the other side of a shield door with the Shotgun or Mauler and kill players as they pass through.

Strategies

 * After swapping for the Spartan Laser when spawning in Team Slayer, if your team doesn't plan on using the Ghost, a good tactic would be to wait for an enemy to get in it, eliminating the Ghost, that enemy, and possibly the Overshield threat.
 * Even though the outside is good for sniping, the Beam Rifle is more commonly used inside for no-scoping and double shots, which is usually rather effective.
 * The rocks (Far Rocks) lined up near the Ghost spawn (Underpass) provide a relatively safe above-ground path from base to base.
 * The bases' ceilings are transparent, allowing players inside to see potential assailants above.
 * The Needler is a very useful weapon on this map.
 * The Maulers on the Tundra Side of the map can prove very useful for players that intend to patrol the Ice Cave.
 * Bubble Shields are useful when protecting the Ice Cave in team games, as players can deploy it when an enemy is trying to get through.
 * From almost the beginning of a match on this level, a majority of the fighting takes place in the Ice Cave or the tunnels leading to it. The team that holds the Ice Cave has the advantage, as the area's tight entrances allow for easy grenade kills.
 * When playing Team SWAT, always jump through shield doors rather than walking through them. If there is someone beyond the shield door, this will surprise him or her.
 * Players hiding near shield doors with a Shotgun may get an instant kill when an unsuspecting foe walks through.
 * When going for achievements, this map is good for Up Close and Personal and Lee R Wilson Memorial. To easily achieve the Lee R Wilson Memorial, rush through a shield door and quickly throw a plasma grenade at an enemy waiting for you to rush him. He'll most likely start rushing you, making a stick easy to accomplish.
 * If you're playing Lone Wolves and you have a dark color for you primary color, for example, steel or purple, you can jump on the control balls and crouch on them to blend in.
 * When you're behind the glass screen in a base, jump on it and crouch on one of the supports on either side. This gives you an upper hand when using a close-range weapon or, if you have Active Camo and you want to kill stealthily, stick a player. This also gives you a good view out the transparent ceiling.
 * This is one of the few maps that has a Spartan Laser on it by default (and is therefore practically the only map on which to get the Two for One achievement).
 * When playing oddball on this map one may find it useful when carrying the skull to stick in the tunnels. It's much more difficult for enemies to dodge your beats.

Forge

 * In Forge, you can block off all tunnels to the Ice Caves (using mostly Crates and boxes, and Weapon Holders to keep them there), keeping players focused on long- to medium-range combat.
 * In Forge, you can get under the Ice Cave and float around. You can keep going in Monitor form until you come out underneath the Underpass. Once there, you can return to Player Mode and fight; you can build on this area, as it is a solid surface. To get there, simply place a few Crates next to the wall of the Ice Cave and insert a Mongoose. Get on the Mongoose, then get off and quickly enter Edit Mode.
 * To get there, enter the Ice cave and hover along the wall connecting the Ice Cave Entrance to the tunnel leading to Low Base. Move along this wall and toward the Low Base tunnel until you find the point at which the wall curves inward. Place a Mongoose at this point, having it face parallel to the wall's curvature and towards the Low Base tunnel. Then, bring a Crate inside of the cave and use it to shove the Mongoose as close to the wall as you can get it. Hop on the Mongoose, enter Edit Mode, exit Edit Mode, and quickly re-enter Edit Mode, and you will find yourself beneath the cave.
 * You can indeed float beneath the Underpass, though if you fly as far as possible in the other direction, you can get the boundary turrets to try (unsuccessfully) to shoot you through the ground.
 * You can get into the blue rooms underneath the bases, although you cannot exit without committing suicide.

Variant: Boundless
Boundless is a map variant released to improve the gameplay balance, specifically as a response to reports of widespread shotgun-camping near the Shield doors. It was due to be released on September 16th, 2008, along with TU2, but was delayed until September 23rd, 2008. The following is a list of changes made;
 * The Spartan Laser in Low Base has been replaced by a Beam Rifle.
 * The Ghost has been replaced by a Mongoose.
 * The Active Camouflage has been replaced by a second Overshield.
 * The weapons outside of each base has been equalized, with a Covenant Carbine and a Battle Rifle on the side, and another Carbine on the back.
 * In both High and Low bases, the two entrances from the top middle portion of the map still have shield doors. The others have been removed.

Miscellaneous

 * Evidence supports the theory this map is located on one of Sanghelios' moons. This is derived from the fact that Sanghelios has two moons, and one of those moons can be seen in the horizon of Snowbound. The other object in the sky is the reddish-orange planet thought to be Sanghelios itself; Sanghelios is described as (and has been seen in other media as) being a fiery-colored planet.
 * In the Red vs Blue transition to Halo 3, Church shows this map (as well as High Ground and Valhalla) as a place where they can move. Church speaks of property value and how this map, though in the Arctic, could be a good investment should global warming arise.
 * This is currently one of three Halo 3 multiplayer maps that take place on a Covenant-controlled territory, the others being Assembly and Heretic.
 * There are several Automated Turrets, positioned along the outside of the map that will shoot at any players who go beyond the boundaries of the map. If killed by them, the kill will be credited to the Guardians.
 * Like Sandtrap, players may leave footprints in the snow (which could be tracked) for a few seconds before fading away. This is helpful when opponents are in Active Camo.
 * In the Halo 3 Beta, the engine incorporated real time reflections into many aspects of the game. The outside of Snowbound's bases, as well as the Ghost, player armor, and a few weapon holders, utilized the graphical enhancement of real time reflection. However, this was removed from the final version of the game.
 * This map, along with a few others, were originally supposed to feature Shade turrets and Deployable Lookout Towers. They were removed in the released version, though tags for these Forge items still exist within the map's base coding.
 * The default version of Snowbound has been removed from all Matchmaking playlists except Lone Wolves and Rumble Pit. It has been replaced with the Hard Core (HC) Snowbound in which a few changes have been made, which deletes the Spartan Laser and Shotgun from the map and puts the Beam Rifle on the original Shotgun spawn point. Each base now has a Bubble Shield, where the default Snowbound had only one base with a Bubble Shield and another with a Power Drain.
 * On IGN during the time of the Halo 3 Beta, IGN stated that Snowbound was probably inspired by the Battle of Hoth from the Star Wars universe.

Easter egg

 * In the sky, the visible planet has a Marathon symbol on it.
 * In the Active Camo tunnel, there is a Canadian $1 coin (or loonie) buried in the snow beneath the Active Camo, perhaps a homage to the "Lucky Loonie" customarily buried under the ice during Canadian National ice hockey or curling events. The "lucky loonie" was made famous during the 2002 Salt Lake City Olympic games when both the Canadian men and women teams won the gold medal. However, this coin is not seen during split-screen games.