This is for when/if Valve decides to make a third game:

Setting: Green Flu has now spread all along the western seaboard. The military has left, leaving the infection to resolve itself...too bad they were wrong. CEDA is dead, the emergency workers are all dead, and of course, the military has left the survivors for dead. The survivors decide to take a boat at a marina and sail it to a safer location, while trying to get in touch with anyone still alive...

Survivors:
1. Mark: A 21 year old who was in his last year of college. He was going to drop out because of the constant bullying for his sexual identity. He first encountered the infected while leaving for school (the day he was going to drop out). On the way, he had not been paying attention to the road and hit a child.....he wasn't dead. Now Mark wants to just live. He wears a dark blue v-neck, over that is a black hoodie with a skull on the back, blue jeans, and black tennis shoes.

2. Matthew: A 30 year old bartender from New York. He decided to visit his mother in California (where this takes place), who is sick. One morning while taking care of her, she died. She came back minutes later...bit Matthew, but he found out at that moment he was immune. He is almost bald (gray hair), wears a black t-shirt with sleeves rolled up, black dress pants, black dress shoes, and a gold watch.

3. Tony: A single father who had just gotten out of a divorce. He first encountered the infected while driving his daughter to school. The zombies overran the car and took his daughter, but the other survivors rescued him before he was infected. He wears a blue button up shirt, black jeans, and black dress shoes, and glasses.

4. Lizzy: She is the youngest in the group, only 19. She was in church when it happened. She had been alone and praying when the pastor (infected) came for her. She made it to safety. She has a brown pony-tail, a purple shirt with a frowny face on the front, blue jeans, and black converse, with a pearl bracelet.

New Weapons:
2. Double Barreled Rifle: Called Elephant Gun ingame.
1. MAG-7 Shotgun- Called a Mags ingame
3. Rocket Launcher- Only appears once, with 10 rockets

Melee Weapons:
1. Fire Extinguisher
2. Pick axe
3. Shovel
4. Metal Baseball Bat
5. Hockey Stick
6. Pitchfork
7. Nun chucks
8. Mallet

Thrown Weapons:
1. Hand Grenade
2. Acid Bottle (Similar to a Bile Bomb, but it is spitter acid and kills infected)

New Special Infected:
1. Psychopath: Like a boomer and witch, but no bile. This infected has a straight jacket on, and when shone on just once with a flashlight, it starts a screaming frenzy that draws the hoard. It's mouth is large, and when done screaming, it jumps on the survivor and attacks.

2. Twin: A siamese twin (joined together), one side of the body is larger than the other. The large side picks up the survivor and the small one spits bile on the survivor, and while the survivor is still held, it is attacked by the hoard that is drawn in by the bile

3. Crawler: This infected crawls on all fours (hands are backwards), but is really fast and stealthy. It will crawl and jump on the survivor and attack. It is bald, very skinny, with overalls.

4. Doppleganger: It looks like a little girl with ribbons in her hair, but she is faceless. She cries and when you get close, she screams and attacks with her long claws, she goes for one person, but if other survivors try to help she goes for them.

5. Dhamphyr- A vampire-like zombie that can leap VERY large distances (larger than hunters) and when it attacks it'll bite non-stop. It has black hair that goes over its eyes and the eyes glow red. Its biting teeth are large and when it jumps it screeches. It wears a ripped up tunic.

6. Nightmare- Its a girl with very long nails in a dress that is ripped up. Her hair is down to her back and her hair is black, she has a stitched mouth and stitched closed eyes. She will hear your presence when you are close to you, and when she attacks she'll claw aNightmare)
Campaigns:

1. Once More Into the Breach:
A. The Courthouse: the survivors must get out of the basment through the courthouse (Previously an evacuation center), and head through to the other side of town to reach the football field to be evacuated.
B. The Inner City: The survivors must go take a detour through the inner city through multiple houses and stores.
C. The Factory: The Survivors must go through an abandonded industrial factory dodging falling rubble and fighting through hordes of infected.
D. The Junkyard: THe survivors must go through a maze of junk and rubble to safety.
E. The Stadium: The Survivors have reached the football stadium, and have to now call in a helicoptor to airlift them out. But first they must turn on the stadium lights, by going to a generator at another evacuation center, and then gather supplies for the pilot (1 health pack, 1 defib, 1 pills, 1 adrenaline, that are each in separate rooms in the Wells Fargo Building)

2. Backwoods Capital:
A. The Road: The survivors must trek down an abandoned highway to Denver, after a technical malfunction caused the survivors to evacuate the helicopter, which kills the pilot.
B. The Outskirts: The survivors go through the forests of colorado to get to Denver
C. The Capital: The Survivors reach Denver and must traverse through the state building.
D. The District: The survivors go through 17th street, and through many side alleys and streets to reach the spire.
E. The Spire: The survivors must get to the top of the Spire to call in another survivor who will rescue them by hummer. The survivors then must go all the way back down to a nearby gas station, to collect gas cans, and then go to a military outpost to go get signal flares, and fight off infected to create an escape route for the man.

3. Wrong Way:
A. The Backcountry: The driver takes a wrong turn on Interstate 70, and because an arguement leaves the survivors to fend for themsleves in the Colorado forests. There, the survivors decide to trek through the forests, rivers, and hills to get to Crested Butte where the Midnight Riders' tour bus is supposedly stationed at (The rockstars have succumbed to the virus and were killed).
B. The Caves: The survivors come to a series of abandonded caves (Once inhabited by grizzly bears), but are now home to infected.
C. The Camp: The survivors reach a deserted Wilderness Scout camp, and must go through it to reach Crested Butte.
D. The Ski Resort: The survivors reach the famous Crested Butte Ski Resort, and neeed to fight through waves of infected to reach the town.
E. The Butte: The Survivors need to take refuge in the Old City Hall building, but first they need to break into a mechanic shop, then get to the Midnight Rider's Tour Bus, and then fuel it up, and get to Lake City.

4. Rain, Rain, Go Away
A. The Pit Stop: The survivors have reached a gas station, but find the gas pumps destroyed. The survivors then trek through a thunderstorm to the Freeman Mental Institution (Fictional)
B. The Mental Hospital: The survivors need to fight their way through the mental hospital to get to a sewer system to get to Lake City.
C. The Mine: The survivors seek refuge from the storm by heading to the nearby coal mine while fighting off infected.
D. The School: The survivors need to get to the abandoned school, but first they need to get access to the San Juan Mountains by destroying the military wall that separates the Infected from other survivors, by going back to the mine, to find TNT to blow a hole in the wall.

5. The Last Destination
A. The Foothills: The survivors are trekking up the San Juan mountains to a abandoned cabin get to the evacuation center.
B. The Avalanche: After leaving the cabin, the player is separated by the survivors from an avalanche caused by a Tank, and needs to regroup. (This is the only time the player can fight off special infected when they)
C. The Mountain Path: The player as regrouped with the others, and they need to trek up a steep mountain path, fighting off hordes, going through abandoned buildings and cabins, and finally reach the evacuation center.
D. The Evacuation: The survivors are cleared to enter the evacuation center, but an enormous horde of infected have breached the center, and the survivors need to help the military fight off the infected and reach a cargo plane to be airlifted.

Notes:
1. The Witch has bloodier fingers, and longer hair.
2. The Tank looks like the ones in the Sacrifice
3. All Special Infected except for the Witch, Crusher, Tank, and Charger, have both a male and female counterpart:
3. The Female Hunter has a brown hoodie, and pajama pants, and a high pitched scream, it has long black hair that covers the right eye, and has longer claws.
4. The Male Spitter is balding, and wears a holey undershirt, short-shorts, and wears socks and sandals.
5. The Female Jockey has red hair tied into a bun, and wears a sports bra.
6. The female Smoker has a large tumor covering the entire left side of the face and neck, and has one long tongue, and a nose ring.
7. You can dual wield differnet handguns: Like a Glock (The pistol in the left hand when dual wielding in L4D2) in one hand, and a desert Eagle in the other.
8. There is now gore effects for special infected. (chop off body parts)

Special Infected Changes:
1. The spitter is now toothless.
2. The witch wears the Sacrifice dress all the time now.
3. The chargers overall top is now fallen off, and he still has pants.
These are my ideas for Left 4 Dead 3. If it ever gets made. Feel free to add your suggestions, or opinions.