The basic genres are: 
Nuclear Holocaust, Chemical War, Ecological Collapse, Global Epidemic, 
Alien Invasion, Global Conventional War, Global Crop Failure, New Ice 
Age, Social Collapse, and Giant Comet Strike.

	Nuclear Holocaust - Climate Change, Most Cities and major 
Military Bases destroyed, lots of radiation. Be sure to show the 
Statue of Liberty nearly destroyed but still standing glowing with an 
eerie incandescent blue glow. Example: Morrow Project

	Chemical War - Many people dead, but cities and military bases in 
better shape. Pockets of powerful poisons. Be sure to show the 
statue of liberty in the middle of an abandoned city while clouds 
of poison swirl around her. Examples: None.
	
	Ecological Collapse - Climate Change, crop failures, cities
flooded, vital ecosystems disrupted. Many people die slowly and/or are
turned into refugees so social chaos is increased. Pockets of civilization
and/or safety still exist but are fiercely defended. Very
Politically-Correct, be sure to show the Statue of Liberty submerged in
water up to her armpits. Makes eco-liberals yammer about the rainforests.
Examples: Ark I children's TV show from way back. 

	Global Epidemic - Uncontrolled bio-war agent or natural disease 
kills off most people. Most people die quickly, but there is plenty of 
chance for riots, panic, and destruction in the cities. Most places are 
barely touched giving characters access to amazing resources - as long as 
they last. Danger of getting the (fatal) disease. Less social conflict 
because survivors widely scattered. Be sure to show the Statue of Liberty 
standing in the middle of an abandoned NYC with dead tourists crumpled 
piteously at her base. Examples: The Stand

	Alien Invasion - Aliens (or any non-human and unfriendly species)
land and take over the world. Humanity is either subjugated or
exterminated. Hazards include evil aliens and their minions. Humans are
rebels against the existing order. Nice red-blooded patriotic potential. 
Be sure to show the Statue of Liberty pock-marked with laser burns but
still standing proudly with Old Glory waving in tatters behind her. Makes
Republicans weep with pride. Examples: Invasion Day, V, Terminator, The
White Mountains, The Planet of the Apes, War of the Worlds. Probably the
most common Post-Holocaust Genre. 

	Global Conventional War - Civilization gets hacked to pieces bit 
by bit. Cities wrecked by fighting and/or bombing. Everyone except 
military on strict rationing. Martial law. Lots of refugees. Lots of 
former soldiers turned outlaw. Possible take-over of U.S. by hostile 
foriegn power. (In the latter case, more role-playing for red-meat 
Conservatives. Be sure to show the Statue of Liberty pocked by RPG-7 
explosions with her torch knocked off and a Soviet flag put in its place. 
Sure to get the blood pressure up down at the VFW.) Examples: Mad Max, 
Twilight 2000, Red Dawn, 1984.

	Global Crop Failure - For some natural or (more likely) unnatural
reason most of the world's food crops fail. Most people die of starvation.
Martial law. Food riots. Refugees flee into the countryside looking for
food destroying farms and killing farmers making things worse. Cannibalism
common. People live on glop made out of algae or worse and consider
themselves lucky. Another Politically-Correct genre. Makes Greens whine
about the dangers of mass mono-culture and/or the demise of the family
farm). Be sure to show the statue of liberty standing in the middle of
cornfields planted at her base. Examples: Autoduel, Soylent Green

	New Ice Age - The glaciers move south in a hurry, burying every
city north of the Mason-Dixon line and/or Spain. Global climate change (to
say the least!). Massive refugee movements. Massive starvation.  Most
cities destroyed. First World suddenly becomes poor and hungry. Third
world might become rich (due to improved climate). Another 
Politically-Correct genre, be sure to show the Statue of Liberty buried 
up to her armpits in snow. Examples: None that I can think of.

	Social Collapse - All the criminal scum-bags get together to take 
over society. Rape, murder, robbery, and not giving your seat to little 
old ladies on the bus become commonplace. Food riots common until the 
Mafia machine-guns the rioters. Organized brutality and corruption. Dogs 
and cats living together. Bad character actors. Head villain's hideout is 
in the base of the Statue of Liberty, even if the movie is set in L.A. 
Some really bad movies have been based on this premise, notably Escape 
from New York and Escape from Los Angeles.
	Alternately, overpopulation forces people to live under martial 
law and die when they're 30. They all live in sterile underground 
complexes and listen to bad 70's rock music. See Logan's Run.

	Comet Strike - It killed off the dinosaurs, so why shouldn't we 
die the same way? Massive climate change, crop failures, food riots, 
massive panic, destruction of coastal cities (if an ocean hit by the 
comet), possible loss of atmosphere. Be sure to show the statue of 
liberty standing, against all probability, in the middle of the crater 
that used to be New York, even if the comet hit in the South Pacific.


Not a bad mix.  Actually, the fun comes when you consider the mixes: i.e.
Aliens invade, but all they want to do is sell us drugs.  The drugs are
better than anything we could ever imagine, social collapse ensues as
conventinal wars breakout.  In their need for the alien'Joy' conventions
against nuclear, biological and chemical weapons are forgotten.  (Be sure
to show the stratue of liberty with track marks on her raised arm:)


In addition to "The Day After", "Twenty Years After", and "One Hundred
Years Later", there's "Ten Thousand Years Later". I know, this is 
largely a sub-set of "One Hundred Years Later", but you can either have 
a complete and interesting new civilisation grown up on the ruins, or 
you can go for a tacky surprise ending when the teenage caveman comes 
round a corner and discovers the last bit of the Statue of Liberty, 
telling the audience (if not him) that what they thought was ancient 
history or another planet is actually A Horrible Warning.


Arguably a sub-set of some of the others, but worth a mention; The 
Robots Take Over. Cybernetic designers get too successful while failing 
to read enough Asimov, and the electronic brains decide that they can do 
better than us, even at being nasty. This allows for various plots, but 
most of them involve guerilla warfare against big killing machines. 
Permits variations such as trans-temporal guerilla warfare vs. big 
killing machines with Austrian accents (or slightly smaller ones with 
bigger FX budgets). Be sure to show the Statue of Liberty largely 
demolished and probably being dismantled for scrap metal, surrounded by 
a clanking, depopulated, robot metropolis. Examples evolved through the 
paranoid SF of the '50s, and mutated in the paranoid SF of the '60s to 
give us Ellison's "I Have No Mouth and I Must Scream". In the paranoid 
SF of the '80s, the sub-genre returned in the form of *The Terminator*, 
which of course got a (paranoid) sequel in the '90s. Cross-reference to 
Harry Harrison's *War with the Robots*, Keith Laumer's "Bolo" stories, 
and Saberhagen's "Berserker" stories. Game examples; *Ogre* (sort of), 
the ever-wonderful *Rivets*, *GURPS Reign of Steel* (upcoming).



Basic Neglect -- For whatever reason (a religious revolution, the
"appropriate technology" fallacy taking hold, lack of resources,
whatever), a generation decides to give up high technology and all of its
benefits.  Things like cars and pacemakers are seen as magical devices.
Two-story buildings are considered dangerously tall.  The Statue of
Liberty is covered in rust because nobody knows how to maintain it.
People who know how to make technology work are either gods or demons.
Example:  the "Unnight" adventure from an old Space Gamer, later released
as a GURPS adventure.