Mongoose Mowdown

Mongoose Mowdown is considered one of the more difficult Halo 3 multiplayer achievements to get, along with Two for One. It is awarded for splattering an enemy with a Mongoose in a ranked free-for-all playlist. This achievement usually unlocks the SCOUT-class Mjolnir shoulder piece for Spartans, but the shoulders have been unlocked without this achievement for some players. The achievement awards the player 5 Gamerscore. Currently, the only ranked free-for-all playlist is Lone Wolves.

It is represented by an orange circle with a Spartan driving a Mongoose, three red stars, and the flying body of a Spartan.

Tactics

 * Players cannot easily be killed by simply driving into them – the direction that the player is headed in is important. If a player is heading in the same direction as you, they are very difficult to splatter.
 * The basic approach for getting a mongoose splatter is to think of the map as a giant racetrack. You want to be moving at full speed at all times, and you want your racetrack to pass through areas that give you cover but don’t slow you down – like the caves on Valhalla.  You never want to stop or slow down for anything; doing so will get you killed.
 * One of the easiest ways to achieve this is to play on Isolation, and drive a Mongoose around in a circle on the bottom side of the map. You can think of Isolation as either an oval or a figure 8 shaped driving tracks.  Go around the bottom level of the map and drive up the sniper hill for easy splatters.
 * High Ground is a bit more difficult to get the achievement on, but it is possible to get it here. Drive laps around the beach and be sure to pass through the caves leading from cloak to the sniper rifle.  It is also possible (yet risky) to attempt to traverse the entire map by going back by the base, driving through the fence, turning back and traveling through the center main gate to return to the beach area.
 * Another tactic is to have someone with a brute shot on the back of your mongoose. If a brute shot is fired at the ground, it will make the mongoose fly through the air, allowing you to splatter people that try to jump out of the way.  Having a passenger shoot people in front of you, however, it is a bad idea if you’re trying to get a mongoose splatter; all it will do is alert them to your presence.
 * The reason that this achievement is so hard is that there are only a few angles you can goose splatter an opponent from. If an opponent is heading directly towards you, it is possible to splatter them by just hitting them at full speed.
 * If your victim is not headed in the same direction, the best way to splatter them is to lead the target slightly so that they walk into the side of your mongoose just as you run into them.
 * The easiest target to splatter is one that is in the air.  If you manage to hit someone just as they are hitting the ground, not even an overshield is going to save their lives.
 * There are a few weapons that novice mongoose drivers tend to get destroyed by that are easy to avoid – Spartan Laser, snipers and Archer missiles. The best way to avoid getting killed by any of these weapons is to not head directly towards or away from a person wielding one of them.  Most players will end up missing you if you’re moving at an angle.  Also, try to think of objects you can drive past that will break their line of fire.
 * Keep in mind that you never want to quit moving, if you see someone that you think you can hit but hitting them will make you come to a dead stop, chances are you’re going to miss and then die. However, the more confined the space you head into, the more likely you’re going to walk away with a mongoose splatter.