First off, I must give credit to TheGreatBrownie, for without his "Hectic Highway" map/gametype, I wouldn't have been inspired to make my own version. I pretty much took his idea and created my own interpretation. You can find the original thread for "Hectic Highway" HERE. And now, back to the show...

Map/Gametype Description:
Highway A&D is a 2v2 one bomb assault game played in the Sky Bubble section of Sandbox. Each team will spawn on their own "highway", with their own objectives. The Attacking Team will spawn on the "Blue Side" (as indicated by the blue columns), and must reach the end of the highway via Mongoose. Once there, they will find the bomb which one member must pick up and carry a few feet to the bomb plant location. The Defending Team will spawn on the "Red Side" (as indicated by the red columns), and must chase down the Attacking team and prevent them from planting the bomb. The team with the most bombs planted in 10 rounds wins the match.

The rest of the map/game details will now be explained via a picture tour! I will be your guide, so follow me!(captions will be placed under the picture)

http://haloscreenshots.net/gallery/CF543510FCCB580FDAE715EAF99D9616/
Seen here are the spawn areas for both teams. As you can tell, the Attacking Team (foreground, blue columns) has a bit of a headstart. One large block in length to be exact. Both houses a Mongoose, but the Defending Team spawn area will also house a single Fuel Rod Cannon.

http://haloscreenshots.net/gallery/AC1605155A91F3186CBE6D8015F6DE92/
10 seconds in, ramps spawn, connecting each team's spawn areas to their respective highways. I wouldn't hang around much longer if I were on the Attacking Team though, because 20 seconds in...

http://haloscreenshots.net/gallery/A8447289063BE6F210CF12796D9BD502/
...a Killball will spawn, killing those who think it's funny to hide from the Defending Team.

http://haloscreenshots.net/gallery/E12983CD54C15C2EA7FFAA16F2E6D91C/
About a third into the highway, the Attacking Team will have to make a choice. Expert driving can only get you so far, choosing wisely at this point can be the difference between winning or losing. The 3 choices are...

http://haloscreenshots.net/gallery/72DE7E102A1E70B07B30D41A461F84A1/
...Route A. This route may be the shortest distance between the spawn and the "End Zone", but it's also the most open to enemy Fuel Rod Cannon fire than the other 2 routes. There are a couple slaloms, but it shouldn't be a problem to expert drivers.

http://haloscreenshots.net/gallery/E6D78BD95AB63DD0D2A236E2445BC1D0/
..Route B. This route leads directly above Route A. Taking this route will add a few split seconds to your run, giving the Defending Team a chance to catch up slightly, but you are shielded very well from enemy Fuel Rod Cannon fire. In fact, there are only 2 small windows of opportunities that the Defending Team will get to stop the Attackers...

http://haloscreenshots.net/gallery/97454B8C219A4431B02936D7DF5FE304/
...one of which can prove quite disastrous for the Attacking team should the Defending Team have accurate aim and timing.

http://haloscreenshots.net/gallery/6E7B47E39C977D834C029FF05E296D08/
Route C leads to the right of the other 2 routes. Technically, this is the safest route to take in terms of enemy Fuel Rod Cannon fire, but one slip-up on the driver's part can mean losing the round.

http://haloscreenshots.net/gallery/C31D655EF1B89A5858880EA3386EE86D/
Oh, and if you're taking Route C, drive safely, but also drive fast; you're going to need to jump a gap at the end.

http://haloscreenshots.net/gallery/BA78D2921EFB3E5ECEF9EDF9022C9298/
If you make it past either of the 3 routes safely, you will find yourself in the "Final Stretch". You'll notice a narrow section that you must cross. Do so, and you will arrive at...

http://haloscreenshots.net/gallery/481985C8DC9341CE17DE14EFDE937321/
...the "End Zone" Get off your Mongoose and walk past the shield door before you get hit in the back with Fuel Rod Cannon fire. A Grav Lift keeps you from coming back out once you have crossed to the other side.

http://haloscreenshots.net/gallery/0F531911A534F0CB57D25E33DAB8398F/
Once on the other side, pick up the bomb, and plant it at the bomb plant location just a few feet away. Be careful though, because at the end of the Defending Team's highway is...

http://haloscreenshots.net/gallery/1ED2B0942B4EE1CD7116F36C9D77820A/
...what I call the "Clutch Cannon". This is the Defending Team's last hope of stopping the Attackers from planting the bomb. It will launch the Defenders into the air, doing two things: 1, it will send them to their deaths, and 2, it will give them an open view of the Attackers in the End Zone, as well as their final opportunity to stop the Attackers from planting the bomb.

http://haloscreenshots.net/gallery/FD7C9E743FF5B64B733C4D14CD58F6AC/
Here is a view of the 2 highways from the spawning area. The left side is for the Defenders, and the right side is for the Attackers.

http://haloscreenshots.net/gallery/62BE52527622D8AE60C3EBD1945D725F/
Here is another view of the 2 highways. You can't tell from this shot, but the columns that act as cover for the Attacking Team get spread further and further apart as it gets closer to the End Zone.

Some things worth mentioning:
- I originally wanted to name this map/gametype "Highway Assault" but Bungie changes it to "BLAM!" because of the "ass".
- 4 players are required to play this game. No more, no less.
- Everyone spawns with a Plasma Pistol. The guy riding "shotgun" on the Attacking Team can use it to slow down the Defenders.
- Infinite Ammo is enabled.
- The shield doors found at the end of the Defending Team's highway are there for a reason. They're there to force the Defenders to use the Clutch Cannon.
- Picking up the bomb will decrease your movement speed to 50%

Download the map HERE.
Download the gametype HERE. (REQUIRED)