This is a Foundry infection map that effectively utilizes switches while keeping the gameplay smooth. The map is basically a human fort with three gates, two of which you can close. After reading SergeantSarcasms forging 201 tutorial, I MASSIVELY changed this map. I took away weapons, lengthened spawns, and lessened ammunition. There are a few things that an infected may randomly get to help them out. To provide the curve of deaths at the beginning, the Alpha Zombie will start out with either one of two advantages (covered later).

Overview:

Human Spawn: In the picture I am shooting at a plasma grenade that never respawns that you need to set off the first switch. You throw the plasma grenade behind me in the hole in the wall.

Beta Zombie Spawn: The Beta Zombies will spawn in the cave with the shield door, and the active camouflage is for zombies, humans will rarely get it.

Alpha Zombie Spawn: The Alpha Zombie must walk through a tunnel to give the humans some time to prepare, and at the end a teleporter will take the alpha zombie to one of two places: Either inside the humans' base, or in the overshield tunnel just outside of the base. This is to provide the kill curve explained in the forging 201 tutorial by SergeantSarcasm.

Overshield Tunnel with Alpha Zombie Receiver Node:

The First Gate: The plasma grenade triggers it to close, or it will close 3 minutes into the game.

The Second Gate: It closes by grabbing a custom powerup in front of it.

The Third Gate: Not Close-able.

One of the trucks is rigged with explosives:

The pit of doom: Your only hope is a shotgun, oh wait, there's a way out, except for the last man standing.

Weapons: (Most weapons are spread-out and have low-ammunition.)
Assault Rifle x4
Battle Rifle x4
Shotgun x5
Sniper Rifle x2
SMG x5
Magnum x4
Rocket Launcher x2 One never respawns, while one doesn't place at start and is hidden.
Flamethrower x1 Never respawns

Equipment:
Frag Grenade x8
Plasma Grenade x1
Firebomb Grenade x2

Gametype:

25% Initial zombies
Alpha Zombies and Beta Zombies have the same traits.
Last Man has a waypoint to everyone, radar increased to 25 meters, and can no longer use turrets.
Next Zombies are the chumps
3 rounds, each to seven minutes
You start with an SMG, no grenades, and a ten meter radar as a human.
Zombies respawn in 5 seconds.

Dl Map: Bungie.net : Halo 3 File Details

Dl Gametype: Bungie.net : Halo 3 File Details