Magic should be just another form of technology, a means to do things. In most games, it is nothing more than another weapon. Others utilize it as a tool of everyday life. There are two axis that magic should be judged by:
Rare/ Common: How often does magic touch the lives of people? This is not adventuring people, this is the entire population. How much of the population is touched by magic (including items) of any kind and how many times in their life. If only nobles (and their servants) lives are constantly touched by magic and they constitute only 2% of the population, magic is still quite rare, despite it filling nobles’ lives.
Powerlevel: Minor to Major: How much effect does magic do. Can a single magic user rock a city or is the best they can do is slighty manipulate the weak willed?
If magic is rare, then the loss of magic will have little impact. If magic is common, civilization as they know it ends. In odd cases where one class/ caste are involved with magic, they will have to change and that will alter their world.
PowerLevel determines how much the world will need to change. Will they need to find a replacement for the magic or change their way of life to meet the lack of effect. If magic is required to keep floating castles in the sky, and the magic goes away… unless they create powerful baloons or can make rocked… the castles will fall.
IN MY WORLD….
Society will only change at the top. The Imperium is based upon their mastery of many arts including magic. With the use of their gates, 32 Imperial High Elventi soldiers (and a few hundred Elventi Militia) can rule over an area greater than the Earth’s. The lack of rapid response and the lack of their magical toys will cripple the Imperium’s rock hard control over the Known World. So the world would be less safe. Since the Imperium seldom interferes with local affair, the local governments would continue on much the same way they always have.
Civilization would not fall, the Imperium would eventually shift gears enough to allow their continued rule. Elventi societies of FirstLand would be damaged, given their dependence on HearthStones and Tree-Shaping magics. It would take some time, but they would adapt. The Dwarventi would be living in the dark, but they would work on new ventilation and lamps. Most of Humanti life would change very little, as none of their biomes allow for the regular use of high powered magics. The only Humanti land dependent on magic is that of the coastal FourthLanders where the clerics dominate life.
Additional Ideas (7)
Power - low
Magic is not a replacement for technology, but in my realm it is present, and fairly common, with magi and sorcerers being respected and useful members of their communities. On the other hand, the majority of people live their lives without the benefit of magic.
Thus, if magic were suddenly extinguished, the peasantry and burgoise will not be much affected. A few luxury items will go away, but no big deal, their are common items to take over. The nobility will be unhappy as they are prime consumers of magic, but lacking magic, the impetus to develop tech will take over.
One of the reasons magic is not so dominant in my realm is that magic is mainly pitted against magic. Most magic protection comes from threat of magical attack, most magical attacks come from magical surveillance and recon. There is a fairly constant cold war of magical research and developement.
Example: Mortengases Ward Versus Scrying is a very strong and viable warding spell that protects the area warded from divination, and scrying magics. After so many years, a wizard creates a new scrying spell that is able to penetrate Mortengases Ward, rendering the ward obsolete. Not to be outdone, Mortengase has been developing a second version of his ward and tailors it to defeat the newest threat to penetrate his defences and those sustained by his allies.
As science, technology, and psionics, are viewed as forms of magic, the complete removal of all magic would only be the result of a complete breakdown of the laws of physics. If those supernatural elements that a modern worldly person might consider magic are removed (as well as ultra-tech indistinguishable from magic), then there would not be major changes to the world. Indeed, the average peasant farmer might only learn of the world's loss of magic through rumour.
Dragons would completely cease to exist. Most extrinsics would die or be spontaneously banished. A few communities would be devastated, as they rely upon magic or their ruling class does at least. These however would be the exception instead of the rule. As magic is not used extensively for food, travel, communication, war, or government, life will continue largely without interruption. There will be some minor shake-ups--especially from a 'trickle down' effect--and most pc's would have a difficult time adjusting, though.
Before the change, magic was very common. The term One Thousand Magics was common as the diverse number of methods used to weild magic. Many funtions in life were aided by magic. Commoners and serfs, slaves and the like had little contact with magic unless their masters had access to it. The rich merchants, upper class, and nobility often used magic to make their lives easier.
Merchants would use it to transport goods without the need of hired guards for protection. They could protect their goods from theft without having to hire protection as well, making shipping and storage of items much cheaper and the ability to send much more quicker.
The upper class having come used and dependant on some forms of magic were shocked and confused when it was taken from them. When the mortals made war with the Gods using the very same magics that were graciously given to them, the Gods were angered and fearful of their powers and took the ability from them.
The world was thrust into a Dark Ages and those who were dependant on magic lost everything. Power shifted and new rulers were put into power after removing the weaker from the thrones of the world.
When magic returned in different form, it became a silent affair. Everyone was afriad to have history repeat itself and kept magic to the basics, not allowing themselves to be dependant upon it. The new magic was different from the old and did not allow the numerous possibilities as it had before. The world copes with it and strives to build a balance between practical use and unneccessary use.
To determine the results of magic removal from an entire world, one must think of magic as we would technology. If a heavily technolitized world, such as our own, were to lose all technology, society as we know it would fall apart, and the third world would rise to the fore-front, having been without technology for long enough that they aren't affected.
Similarly, if a heavily magic-based world were to lose all magic, those without magic (the third world of magic) would likely become more powerful than those who had it before, due to knowing how to live life without it. Or, as was the case in the Chrono Trigger video game, the magic users from Zeal were cast to earth to live in the ice ages with the earthborn who couldn't use magic, and were forced to become equals in rebuilding the world with those "lesser" than them. When one loses one's superiority, one quickly realizes how equal the rest of the world is to them.
However, in both cases, if a world/people isn't absolutely dependent on magic/technology, they won't be affected as bad.
It could probably be summed up by the statement: "A world will be affected by it's loss in a direct ratio with how much it relied on that which was lost."
In the other world, without magic, the dead would invade the world of the living. Apart from that major problem, most other things would be unaffected as magic users are not very common.