Basic Theme:

A Comet struck Earth roughly one year ago. The resulting tidal waves, storms, and earthquakes shattered civilization. We had grown too dependent upon our technology. Every society is only three meals away from revolution...

Physical Setting:

MidgardMOO is set in the remains of an affluent suburb or satellite community of a nameless west coast city (probably Seattle or Portland, but don't quote me on it). High enough in the hills to avoid tidal waves, and rural enough to make the transition to an agrarian community. Most of the inhabitants are new, many of the original land owners had left on the Day and were not able to return. The govenor is an exception. The houses are fairly spread out, and there is little useless (ex)infrastructure to get in the way. Most of the village is in the foothills of a mountain that spreads to the southwest, south and southeast. These mountains are not used by the village, but some people do live in them. A stream feeds its way down through the mountains, passing the village just to the east. This stream eventually flows into the slowly receding inland sea to the northeast. This new sea is the result of the comets impact, drowning millions of acres of land under maybe ten feet of water. Of course, there are islands out there, many with people living on them cut off for the most part from the mainland. Also, the remains of dead towns are out there, and there are rumors of whole communities living in the second stories of such towns. Fields lie to the north of the village, in the actual Valley. Beyond them, to the northwest begins the remains of the outskirts of the Old City. Many of the buildings here collapsed in the impact, and the whole place in general has gone to hell. Many people live there, digging out an abode in one place or another. A complete community lives there amoung the recage of a past age.

Higher level theme:

Beyond the overall theme of a comet impact, Midgard's theme has some finer points.

Ingenuity:

Recovery. Survival. Making do. No one was prepared to revert to an agrarian lifestyle so they improvise. Much of the Valley is a kludge, but it works. Suplies are low and non-renewable. Very few people had the necissary skills, but those who do are in great demand. So things are improvised. Jury rigged. Think of Apollo 13. THAT is the kind of situation we're in.

Mystery:

The world has become much, much smaller in the last year. Suddenly, over the ridge is a completely different world. No one knows what is happening only a few miles away, much less across the world. There were a few radios in the Valley, but the power for them is long gone. The power structure of the surrounding areas is a mystery. There are persistent rumors of warrior groups, yet so far none have shown themselves. There are a number of small groups of people who have united much the same as the Valley, but none are nearly as large or as well situated. People report seeing strange things at night, and all sorts of mutants are said to live in the Old City. The Inland Sea is full of islands of cannibals, religious fanatics, enclaves of oldtech and everything else imaginable. NONE of these have every been documented, of course.

Maps:

General Map of Physical setting
Detailed Topology Map

Additional Resources:

Lucifer's Hammer by Larry Niven and Jerry Pournelle
The Postman by David Brin
Folk of the Fringe by Orson Scott Card
Alas Babylon by Pat Frank

Music:
Firestorm: Songs of the Third World War by Leslie Fish (Good luck finding it! Dealer rooms at SF cons are about your only hope.)