Drama almost always involves information differential, some situation where some people know something and others do not. Dramatic tension almost always emerges from lack of information, where misunderstandings or differing access to information create different motivations. In some stories, information differential can create conflict where everyone is acting in good faith, but at cross purposes. (admittedly, these are some of my favorites)
However, managing information differential in a LARP is a complex process with several different aspects. A properly managed information differential involves the selective guarding and revealing of PC and NPC secrets, the encouragement of the experience of learning and discovery, and the distribution of knowledge as power.
Secrets and Rumors
One of the most straightforward engines of drama in a LARP is the secret. Some aspect of a character that, if revealed, would change the way other characters perceive them. This information differential is an excellent way of creating personal drama for a character, as the process of holding the secret influences the way the character is performed(I can't tell them I'm a spy for the British Government, but I have to ask some leading questions to get information). The selective revelation of the secret becomes currency of intimacy and trust, creating or growing character relationships.
The most important aspect of secrets is that they should matter and change. Secrets should influence decisions, should motivate actions, should create drama. And while characters may not want it to happen, all secrets should emerge over the course of a story. The key to information differential in a story is that it should be dynamic. It should influence the development of the story and have motion to it. As more characters realize that one character is a vampire, they all have to make decisions as to how that affects their relationships. If none of them ever learn, those relationships are never changed by the revelation, so the story is static.
Rumor systems can help with this, providing a method for driving the revelation of secrets in a slightly uncontrolled fashion. This lack of control ups the drama factor of having a secret, adding doubt and fear to the process. You never know who's going to learn about your deep, forbidden love of Chik-Fil-A.
Maintaining the Fun of Discovery
At the risk of sounding like a big nerd(too late), learning is fun. Discovering new information and knowing more than you used to is a pleasurable experience. It's also a key aspect of character development. As you learn new things, you change and become different than you were. One of the keys of managing the release of information is that the fun is important. If you forget to reveal information, you are forgetting to add the fun, which is one of the biggest mistakes you can make.
Revealing information is also by itself a reward for positive play, a way of giving back to those who engage with the world in a creative way. Increased knowledge can be a way of rewarding play that also adds to the experience of those around the player, because knowledge has a tendency to spread outwards in a way that has the potential to create shared fun.
One of the rules of thumb I use for this is to make sure that information goes out in at least two different, unrelated places. If the key goal is to have information spread out and have unpredictable effects, having two spots can make that more likely. It also makes the world feel a bit more alive, which is a benefit.
In my experience, though, it is better to distribute information in pieces. There are a few reasons for this.
1. show don't tell: if you just give all the information at once, you are essentially just giving the outline of a story. Which is generally less satisfying to people.
2. allow for the complications of player input: Players will sometimes interpret story pieces in unexpected ways, focusing on certain aspects of a piece of information. By giving it in pieces, the Storyteller allows a level of player input into the plot, creating a feedback channel for player creativity. Don't go all Chris Carter on this and throw out clues that you have no idea what they mean and lean on the audience to interpret them, but do allow player interpretation to act as a Yes, and...
3. pace out the story: it's just more fun to have things happen over a few steps and it makes for more of a story. Stories have beginnings, middles and ends and this is true for microstories like learning a secret as well.
Knowledge is Power
However, it's important to acknowledge that information differential is power differential and to use that responsibly. One of my hard and fast rules of running games is to never use that power against players as an ST. It's one thing to joke about how the things that players don't know about as dangers, but wielding that knowledge can make a game very un-fun, very quickly. Don't exploit that power to make yourself feel important.
As part of this, it's impossible to know how simple or complex a mystery is in a game. It may be simple to you because you see all the different parts, but your players do not have access to your brain, unless you are playing a much more complex game that I am. By the same token, you may accidentally have a set of clues that line up with a player's master's thesis and have them solve the riddle in 30 seconds. roll with it. Give more clues and have a backup mystery if necessary.
