My contribution to the "what to do about the City Campers" discussion; I hope that I won't ramble on too much.
Let's say that one day, everybody staying in a Safe Zone on a cleared floor wakes up cursed - with some trivial effect such as a 50% movement speed debuff or mild, irritating pain. Naturally, this means that those who know how to circulate their prana will do so, and then at least *some* will spread around the knowledge of how it's done. Those who didn't have their circuits opened now have an incentive to do at least that much.
The day after (or the one after that), a different disaster strikes. Doors have been Altered into a "locked" state. A simple prana infusion (i.e. Reinforcement) will break the effect.
The plague coming next would be themed around Alteration - let's say that all blankets in town get turned into uncomfortably itchy materials, and no two shoes fit together. The options? Get new ones (which means leaving the town for either materials or Gil) or use Alteration to change the old ones.
Followup to which would be basic Projection - horror of horrors, all cutlery in town has vanished overnight.
Next up are propably bounded fields - first, as a repetition of Day one with the twist that the curses get promptly reapplied by the visually-distinct fields until they get broken, then by creating irritating enviroment - smog, insect infestation, hot and cold zones, tropical and desert climes, etc. - that the players have to deal with themselves.
Then, mix things up and repeat, with occasional innovation thrown in. Bounded fields spawning annoying insects that spread debuffs arounds. Altering all liquids in town to have unnatural colors and watery taste. Swarms of songbirds screeching shrilly at 5 o'clock in the morning. Thick snow. Heat waves. Droughs and floods. NPCs convinced that players are all unintelligible or invisible.
And so on. The goals are twofold - shake people out of their comfort zones, which will drive at least some to actively join the game, and to hone their skills in magic.
After a couple of weeks of such a regime, the choices before everyone camping Safe Zones will be clear: bear the discomfort, get out of town, or learn magic and spend some twenty minutes or so before breakfast dealing with Kayaba's choice of annoyances for the day.
It would propably be best to seed the town with some sort of Sage NPCs whose only role is telling players how to go around dealing with things, which could then spread by word-of-mouth. ("So, the howler monkeys disturb your sleep and earplugs don't work, eh? Well.. you could make a Bounded Field around your bed to silence the noise. No? What about Altering your hearing? Not interested? Well, you could always get a familiar or a spirit to chase them away.. I could show you how to make one. Not a fan of pets? In that case, what about Alchemy? Trasmuting your walls to not conduct sound, or brewing a Sleeping Draught..")
The end result would propably be a division between Magi, who actively pursue new research and use magic of their own volition (i.e. most of currently active players) and mere Magic Users, who couldn't care less about innovating, so long as they know enough to live comfortably in town.
But then, laziness is a great motivator and once they get into the habit of dealing with problems and discomfort by using magic, it will likely bleed through to other facets of their lives.
And, of course, once they get used to it, things can escalate. Cripping heat instead of annoying. Blizzards instead of cold showers. Riot gas instead of smog.
Ideally, by the time that front lines start approaching those "Hostile Enviroment" levels, people back down would already be used to dealing with more-or-less the same, only to lesser degrees.
That would foster greater exchange of ideas and, hopefully, player involvement, since even Rear-liners would become important for the advancement of the Front.
* * *
If you want to get really nasty, then the "no open warfare" nature of Safe Zones could be used to train players for the wrong side of the Moonlit World - memory modification, personality editation, spying and counterspying, corrupting magecraft, etc.
Perhaps some sort of "Terror From Below"? As more floors are cleared, the lowest floors begin to darken. Eventually, they end in a state of perpetual night, interspersed only with brief periods of twilight.
And as darkness falls, the occupants of the Safe Zones begin to change. More unsavoury characters emerge. NPCs that trade in secrets and sins - offering rewards for stereotypical Magi behaviour, ranging from stealing knowledge to stealing memories to dissections to vivisections. All against mobs and other NPCs, of course - the anti-harassment code can get quite vicious in face of such sort of molestation.
The darkened Safe Zones stay ostensibly Safe - but their atmosphere changes to something straight out of the World of Darkness. Quests teaching not how to navigate a map, but how to navigate a conspiracy. Appraising motives and judging bonds instead of assaying items and grading materials. How to hone a mind rather than a blade. And thorough all of this, the pressure to learn relevant magic increases.
Can't tell lies well? Divine the truth of their words. Or hear their heartbeat and see the dilation of their pupils.
Can't understand other people? Learn how to peek into their heart of hearts or how to make mirrors that show their desires.
Not smart enough for magic? There's a spell for that, too. What will you trade for it?
