Lost Platoon

Lost Platoon is a Firefight map in Halo 3: ODST. It is one of the larger and wider of the Firefight maps, as it contains a Warthog at the map's centre structure. Unlike most of the other maps that are too small or that just let the Covenant drop off Wraiths, this map will also let the Covenant drop Choppers.

Setting
Based off a section of the Campaign level Uplift Reserve, Lost Platoon is set in the Uplift Nature Reserve, a park located next to the metropolis of New Mombasa, which became a battleground during the Battle of Mombasa. By the time the map is set, the New Mombasa Orbital Elevator is still standing in the background. The map consists of a series of buildings connected by walkways in the center of a scrub land-like environment. The name of the map is a reference to the Second Platoon, which is holding position in the area during the campaign level.

Standard Firefight

 * If you have four people, a good strategy is to have one player use the Spartan Laser and Sniper and make him snipe and pick off the Wraiths. Have two players use the Warthog and the third use a chopper. Alternatively, you could have the third player use the Sniper, making the Spartan Laser player use a chopper to get to the Wraiths faster.
 * Save your hammers for the third wave. A regular bash will kill most enemies in two hits, with the exception being Brutes and Hunters. Use the trigger bash on vehicles coming too close or hunters. Save these during Black Eye rounds, their bash will kill enemies fast and heal you as well. This works well when you have a group of enemies, as you can kill a majority of them fast and use the last one as a health punching bag with an alternative weapon.
 * Don't hesitate to splatter anything. Especially with the Chopper, but stay at range when the Catch skull is on, and you're facing enemies who can throw grenades.
 * Do not fire the laser on single targets, save the charge for more formidable opponents like the Wraith or a Hunter.
 * The Warthog will respawn with each weapon drop. Don't be foolish with it. Only drive out when the Phantoms are gone. At the end of each wave, get to a spot where they cannot shoot at you.
 * Snipers have an excellent vantage point on top of the base. You can shoot at any of the drop-off points. However, Phantoms have a shot at you as they enter and leave (and the hill drop off has a shot at you during drop-off). Enemies have a hard time reaching you, except for Wraith mortars, Jackal Snipers, Drones and Jump Pack Brutes.
 * Good spots to hide are under the staircase in the base and behind objects in the spawning rooms. Use this if you're going for your Be Like Marty achievement and want to avoid any type of contact with Covenant.
 * If you only have two players, have one player be a sniper and wraith and the other fight off invading Covenant. Alternatively, two players can use a Warthog and have the gunner take out Wraiths.
 * Drones are very vulnerable to the SMG and Brute Plasma Rifle, save the Magnum ammo for other opponents like Grunts at a distance or vulnerable Brutes.
 * If playing by yourself and on Legendary, getting a Chopper is strongly recommended, as you will have infinite ammo, speed, and can kill enemies at a distance. Alternatively, you can use the Anti-Air Wraith Glitch and take command of a Wraith (who are rigged to explode like AA wraiths are in the main campaign) but without a second person to be the gunner, you will be almost defenseless against drones, thus Chopper is the best choice for mobility and power, effectively a portable machine gunner.
 * Don't try to eliminate Wraiths with the Chopper and the Warthog, especially with Black Eye and Tilt on, they won't get any damage and deal a ton of damage to you, switch to your Spartan Laser.
 * The cliffs on the side of the map make excellent sniping positions. The chopper (with enough patience) can get you to points otherwise inaccessible on top of the rocks. Make sure both Wraiths can't see you as you drive up however.
 * A good strategy is to have a hog team, one person with laser and one person with sniper. Have the sniper and laser get a Chopper ASAP. When the wraiths land, it's the Spartan laser's job to take them out. Once that is done, they should get back on their chopper. When tilt comes on, if possible, get the hog team on choppers.
 * Splattering Chieftains with a Chopper or Warthog is a good way to kill them and save your ammo for later.
 * During the bonus round, using a Chopper or Warthog is a good choice, as you can splatter many Grunts at once, and you don't deplete ammo. However, do not use the Warthog turret if it is stationary (no driver) dismount, remember the Catch skull is on, and you are an easy target.
 * If you're in a chopper and spot War Chieftains, take a step back and deal with the other enemies because the Fuel Rod Gun will take your vehicle out in one hit on higher difficulties.
 * On the final wave of each round, where the chieftains come, it is advisable to reach the roof of the building in the center of the map. Firstly climb the stairs leading towards where the health pack would spawn, then head towards the diagonal concrete beams and walk up one of them, then jump onto the roof. There is another beam that you should walk across until you get to the glass tiling. The Wraith will fire at you but the shots can be dodged easily. The only enemies you can meet up here are Jump Pack Brutes. Kill them and fire down at the Chieftains below you. Occasionally you can see the head of the hammer coming through the concrete beams if you stand on them.
 * The roof can be an excellent vantage point for anyone wielding the Spartan Laser, allowing them to quickly pinpoint the location of inbound Phantoms and alert their teammates, and can use the clear line of sight to quickly eliminate enemy Wraiths. In addition, they can provide further support by picking off enemy infantry with weapons like the Sniper Rifle and pistol. The Wraiths will have a hard time targeting you, as their plasma mortars can be easily predicted and avoided (unless your blindsided by other enemies). However, it is highly advised to either have a second teammate covering you with an automatic weapon in the event of a drone attack or quickly retreat to an enclosed area where Drones are most vulnerable.
 * The best area to take cover from drones, especially when playing alone, is the room the Spartan Laser spawns in. The confined space negates their lateral mobility significantly. Take care that no other enemies follow them in, however, as even a single grenade on the same side of the room can quickly spell death.

Floodfight

 * Arm your Marines with Spartan Laser and have them ride shotgun on the Warthog. If there were Flood Combat Form wielding Rocket Launcher, take it down and swap the laser with the rockets for better efficiency.
 * Marines would also make an efficient work when handling the Warthog Commandeered by the Flood.
 * Beware of the Sentinels, as they were lethal in close-mid range. Always have a plasma weapon on-hand, especially if Tilt Skull is on.
 * Tough Luck Skull would allow most of the Flood to avoid the attack when they were about to be splattered by a player-controlled vehicle. Warthog is recommended since it has a wider radius and can power slide for better splatter kill.

Trivia

 * On the walls inside some garages, one can see work schedule tables identical to ones in the Traxus Factory Complex 09 during Halo 3's campaign level The Storm and Multiplayer level Foundry.
 * Scoring 200,000 points or more on this map awards the player with the Lost Platoon achievement.
 * The name is a reference to the Campaign level Uplift Reserve, as this is the location during the mission where you locate the "lost" second platoon.
 * This level is unlocked in Firefight by completing Uplift Reserve in Campaign.
 * This map and the huge amount of points one can score in a Chopper was made fun of in a Bungie update."Choppers on Lost Platoon Don't Count!"
 * This is the only Firefight map to feature vehicles.