I keep six honest serving-men (They taught me all I knew); Their names are What and Why and When And How and Where and Who.
So said Rudyard Kipling. I don't know what he was on either, but it makes for a damned good intro to an essay.
LARP adventures are a funny breed. Your average LARP, run as a tabletop, would get you laughed out from behind your screen. A half dozen adventurers, frequently ones who have never met before in their lives, get told to go do something, and they do. On the way they get into a bunch of random fights, then they have a big fight, then they go home. (Usually, suspiciously, having far fewer fights than they did on the way in. Clearly wolves only attack heavily armed mobs of humans when said humans are relatively unharmed.) Indeed, a large part of the reason I have avoided having a PC in LARP games for so long is that I find it so difficult to take the entire setup seriously.
In some ways the comparatively detailed and (though I hestiate to use the word) "realistic" nature of the White City serves to exascerbate this problem. It is relatively easy to accept an adventuring party consisting of Rhonan the Barbarian, Blavd and the Off-White Ratcatcher, and of course the honorable Sir Berus D'Ardvark wandering off into the Stormy Wilds of the Kingdom of Generica, its lands blasted in the ancient Mage Wars, in order to knock some Orcs over the head. On the other hand, the White City was designed as a reaction against all that, characters frequently have day jobs, family ties and loyalties. The website includes comprehensive details of codes of laws and honour. Under these circumstances, "adventures" start to feel a little funny.
The trick, of course, is to make proper use of Kipling's Honest Serving Men. Assuming you have enough ranks of Wealth to pay for them.
What?
There are two very important "Whats" you need to bear in mind when designing an adventure. The first is "What is going on" and the second is "What has this got to do with the PCs".
The "What is Going On" part of the adventure is what is commonly called "the plot". The plot could be as complex as "the Duchess Velasquez, disguised as a serving girl, has seduced and murdered a visiting ambassador from the Kingdoms of the East, in order to provoke a war, in order to threaten the interests of the Christofori" or as simple as "The Trogs are coming to get us!". You've all designed plots, that's not a problem.
The "What has this got to do with the PCs" part is often harder. Particularly with more complicated plotlines. Okay, so the Duchess Christofori has seduced and murdered somebody, for the reasons outlined above. Is there actually any way the PCs can interact with this plotline? If there is, is it a way that actually makes sense as an adventure rather than as a downtime action or, for that matter, a freeform. If you can't think of a good reason for it to actaully be an adventure you might want to stick with "the trogs are coming to get us".
Why?
The whys and the wherefores add a bit of depth to LARPs, and this is the time for all those clever-clever bits of politics about trade routes and family ties and backplot backplot backplot. The two big "Whys" are "Why is this happening?" and "Why do we care?". You can make the former as deep, convoluted and complex as you like, so long as you keep an eye to the latter.
It is deeply important to avoid confusing the "Why" of an adventure with the "What" of an adventure. The "What" is the thing the players have to get their teeth into. The "Why" - the politics, backplot, explaination, and exposition - is far, far less important. A good LARP should, first and foremost, have something interesting going on. A good explaination behind it is nice too, but beware of trying to make the players care too much about it.
When
Okay, this one I'll admit is of limited utility on a LARP. The "when" of it all usually boils down "around about now". On the other hand there are some particularly important "Whens" if you choose to introduce Big Concepts. The choices of these, of course, being "Since When?!". It is viatlly important that you make sure that your PCs know in advance about anything that they are supposed to have... well... known about in advance.
How
This is another of the Biggies. It is essential. Essential essential essential. Really important. Vital that when you design a LARP you make sure you work out how the PCs are going to deal with it. Furthermore, it is important that you (a) allow them several options and (b) make sure that the most sensible or attractive options actually make for good encounters. Again we come back to the importance of making sure that the plot you're running makes most sense as an adventure.
There's a fine line to tread here. I do not, of course, advocate every single LARP boiling down to "kill the baddies, go home". On the other hand it is important that a LARP be the kind of situation where "a bunch of heavily armed adventurers" are the correct people to be sending to deal with the situation and not, say "a diplomat" or "an army". This is a harder balance to strike than first appears, because surprisingly few situations actually need a half dozen heavily armed people to deal with them. Which brings us to the next serving man.
Where
This one is often overlooked, but it is possibly one of the most important questions you can ask on a LARP. The terrain determines what dangers the party will face, what options may practically be considered to be open to them, and how likely they are to know what's coming.
If at all possible set your adventures somewhere inaccessible. Anything you are likely to be able to achieve through an adventure, you are more likely to be able to achieve with a diplomatic envoy, caravan train or enormous army. If, on the other hand your adventure takes place miles into the northern mountains or western forests, or deep amongst the ruins of the City of Chains, it makes a lot more sense to be relying on Adventurers.
Bear in mind your location when designing encounters. Bear it in mind also when the PCs are faffing about between encounters. Remember that while shotover is a calm and safe place, most of the places you're going to be adventuring aren't. Try to develop, when you're designing your adventure, an image of what the area is really like, and do your best to share this with the PCs. Do your best to make them forget that they are on a nice piece of common land in Oxford, make them feel that they are in a black fairytale wood that wants to eat them alive.
An important thing to bear in mind here is pacing. For obvious logistical reasons, encounters are set roughly equal distances apart, on Shotover, nicely out the way of any dogwalkers. There is, however, absolutely no reason that encounters should be evenly spaced IC. If the players are travelling downriver to the Port of Glass, you could let them get the entire way without a single hostile encounter. After all, people travel through the Garden Lands all the time, the more random bandits you introduce, the more you damage the feel of the setting.
Who?
The final question. Who are the PCs. Or, more to the point, who should the PCs be? When thinking about "the mission", think about the sorts of people that are going to be needed (or are going to be expected to be needed) on it. Another thing that - in my humble opinion - shatters suspension of disbelief is the arbitrarily enforced co-operation of characters who have no reason to work together.
There are two angles from which this problem can be addressed. Firstly, players can do their best not to create PCs who are too obnoxious, too antisocial or too much of a liability for them to have any credibility on a LARP (untrustworthy finks who run away from every fight, then steal all the treasure fall squarely into this category). Secondly, GMs can get the adventure synopsis out in time that players who have characters that fit the adventure will be able to speak up and book their places.
Ultimately, the important thing is to think things through properly in advance. I am considering putting together an informal system for this, which I will post on this site when complete.