http://www.bungie.net/Online/Halo3UserContentDetails.aspx?h3fileid=49053264
(click t3h picture)

Technical Stuff:
What I consider to be a huge improvement over my last map, "Pyroclast" (link in signature - I'm not going to spam you with my links), Circulation features even more extensive use of interlocking and geomerging of static objects, even combining the two procedures in one of the most frustrating structures I've ever forged. While I can't boast "total geomerge/interlock" status with this map, I can say that it is a huge aesthetic improvement over the last map.

Unsurprisingly, the tiny size of the map limits party size considerably. At any time, there should be no more than eight people playing this map (even with seven of us, the chaos was intense).

Perhaps my biggest blunder (which I'll fix if and when I remake the map) is the fact that I neglected to use the budget glitch. Seeing as how it is such a small map, I never expected the items to run the budget down so quickly, and as the end of Forging approached, I found myself more and more hard-pressed towards frugality (and by the time I realized the budget glitch would be needed, it was already too late to activate it). The result was that I was only able to place one weapon on the map.

My choice of weaponry was a single Gravity Hammer, placed dead center on the cross-bridge, as a pin through the center of the map. It only ever appears in assymetrical games, as the defenders will need all the help they can get to stave off attackers with their objectives. I chose the hammer over other weapons mainly due to the pathetically tiny range it offers. While its damage resounds for a considerable distance, it is only lethal in a very small space. Still, when I remake the map, there will be more weapons to choose from.

The Map Itself:

First some screenshots so you can see what I'm talking about:

Overview...

OMGWTFSOCCERBALL?!?!

Map...

Circulation consists of a single three-levelled room with four hallways that lead to an outer ring. Built around a circle, every part of the map reflects it in some way. In the middle room, the lowest level is the smallest, most inclosed area on the map (represented in the bottom picture above by the gray portions at the center). At only three single boxes' diameter and half a box's depth, it is a great place for a showdown.

Above that is the crossbridge area (represented by the white area above - diagonal lines being where it goes under the level above). Employing four bridges that meet at the center, this level is where most of the fighting occurs. Also on this level are the four "steps" - the means to jump from the bottom level to the top without the use of a grenade.

And the top level of the inner room (represented by the black area above, diagonal lines being where it is above the level below) is something akin to a catwalk. Its width is that of a single box, and the only things therein contained (besides the height advantage) are the spawn points present and a few of the objective points.

Following the hallways will lead you to the outer "Ring of Death" (represented by the dark gray ring above). A narrow, circular hallway skirts around the perimeter of the map at a larger diameter, and houses the objective points for the defenders, along with a creative (and annoying in a good way, according to those who've played it) mechanism.

In the map's description, it says something about it formerly being a water treatment plant, and this is what my mind cooked up. In order to filter the water, it first needed to be dumped into the center room and then pumped through the (now absent) filtration systems in the map's hallways. What exists in the Ring of Death is the pumping mechanism (read: man cannons and soccer balls in constant motion). It only exists in Assymetrical matches, providing aid to the Defenders by threatening ever to damage the shields (only shields?! Come on Bungie! Soccer balls twice my size can definitely kill me...) of the Attackers. While most people will likely be annoyed by this, version two will likely not incorporate this function into the design (although the outer ring will be there, it'll just be less "of death").

Gametypes:
Fish Out Of H2O - KotH
Actually, it plays more like Slayer than King of the Hill. The premise of it is that the entire facility (map) is under water, and is gradually being emptied. Using damage, gravity, and movement settings, the "hill" is actually the place where you are under water. Your shots do less damage, you can take more hits, you move slower, and can jump higher while underwater. However, as the water level goes down, things start returning to normal. Three rounds of three minutes or fifteen kills, the game tends to go pretty quick when the only weapon available is a Battle Rifle with infinite ammo. Recommended for 4-8 players.

Non-special gametypes supported:

Slayer (all variants, though I would call you insane if you wanted to do rockets on this map)
Capture the Flag (Multi-Flag and One-Flag)
Oddball (all variants)
Infection
VIP
Juggernaut

Tips & Tricks:

Three pieces of advice.

1. Use the Multi-Levelled-ness. When you're under attack in the main room on the cross bridge and need a moment away from the action to let your shields recharge, it's a good idea to drop down to the level below you for a few moments' cover. Usually, it's less hairy down there...

2. Take Advantage of the Pump. While the soccer balls can be annoying, they're also incredibly efficient at dropping a player's shields. If you're clever, you can maneuver the Ring of Death and prey upon unsuspecting victims whose shields fall to the wrath of the soccer balls.

3. Bounce 'Round the Ring. I have yet to see this done, but I do know it to be very possible (and rather cheap). In a game of oddball, it would be greatly to your advantage to take the ball into the Ring of Death and jump into the man cannons. Keep jumping, and it will take you around the ring at a pace that is very difficult to kill. Of course, the way to stop this is to simply get in the way of the jump, but good luck surviving the incoming beat-down.

Action Shots:

The bodies haven't hit the floor yet...

Two duels happening--too bad they don't care about the other one they're shooting across...

Looks clear up here...

Now that just looks like an epic duel about to happen.

The Chase...

Shoot up, I say!

Standing victorious over foes slain.

Credits:
God (for everything)
Nielsen's Homescan Consumer Panel (for giving me hours on end of doing absolutely nothing)
Zachary9990, Rethal Sepsis, Pink Pineape, FattyFatFat Kid, Flames290 and the others in the room (for testing, playing, and giving me the most epic screenshots EVAR)
Bungie (for creating Halo)
ForgeHub (for showing me how to do it and giving me a stage to perform on)

That's all I've got.

Download Circulation
Download "Fish Out Of H2O" Variant

Feedback is wonderful: please, if you should download, tell me what you think.