Sorry about the links, you'll just have to copy and paste them. I will fix them later.
Download Here:
http://www.bungie.net/Online/Halo3UserContentDetails.aspx?h3fileid=69901060
Download Gametype here:
http://www.bungie.net/Online/Halo3UserContentDetails.aspx?h3fileid=69901088
Description.
This is my second post here on ForgeHub, and as far as I know, this is unique. Please read the description, as it tells you much.
Are you tired of playing Demolition Derby on Standoff or Rat's Nest? Do you find the platform to small, or do you find getting outside of the map annoying? Well, Demolition ROCK is for you. (I got the title from a very fun FPS, WarRock. Nope, I'm not advertising.)
Demolition ROCK is on Sandbox, and stationed in the Sky Bubble, for the "falling off a cliff" effect.
The platform is large enough to support 16 people, and is larger than the standard Standoff or Rat's Nest platform. There is a Killball in the center, but is very high up, and collisions are extremely, EXTREMELY rare. During the 4 hours of testing, the only collision occurred when a Ghost flew over a tilting warthog.
There are timed effects on this map, you can see that in the pictures.
There is also a gametype for this map. It's called DemolitionDerby, and it has some unique traits. There is a unique scoring system, as you will see when you download. Assassinations and melee beatdowns are worth -8 to your score, while a regular kill can earn up to 3 points. There are 10 rounds to it, with each round being 3 minutes (for a reason, hence time effects). You go slightly slower than normal (90%), but cannot get splattered. You have regular (100%) gravity and start off with two frags. You spawn with a pistol and unlimited ammo, and you can pick up things (ea, grenades).
You can, of course, use a different Demolition Derby gametype if you wish. If you would like to allow assassinations and splatters, you may find an different gametype that allows so.
Honor Code.
You must obey the honor code of this map, or you will be at option to Das Boot. Do not, and I repeat, DO NOT, attempt to assassinate or beat down. You will be noticed for your low score and be shunned. If the leader wishes to play a different gametype, the leader may.
Now, onto the screenshots! Captions are good for you.

An overview of the map, showing the even vehicle distribution.

Spartans and Elites spawn next to a random vehicle.

Note the blue glow in the center of the map radiating from the ground. This was done purely for aesthetics.

At one minute, two brute shots spawn. These can give you an advantage over charging vehicles, and make funny death moments.

At 90 seconds, two choppers spawn. They have excellent ability to swerve from oncoming vehicles, and the shots carry a punch.

At two minutes, darkness falls. This severely impares someone's sight, and falling off the edge is much more common. Don't camp in the middle though, as you will be punished.

The punishment. If battles are still raging at 2:30, two additional Killballs provide instant death, with a small barrier to walk around.
Now, onto action pics. Provided are additional sad humorous captions.

Dances with Grenades.

It's a long way down...

Free Fallin'

Ridin!

Ninja power!

Collision

A brutal shot (heh, get it?)