How do you structure your adventures?

[Thinker]

Rather than talking about campaign settings and fictional worlds, I'd like to talk about adventures. From fighting off the Horde to saving the Sole Monarch of the Eternal Empire, there's a lot of ways to build an adventure so what do you prefer to do? How do you prefer to engage your players in it?

Lately, I've been more about building a situation that looks like it could turn out badly. As the players do things to muddle up the situation, the situation progresses or changes to adapt to their interference. Hopefully, by the end they've stopped the sinister forces. Most of the time lately, I've been presenting a teaser about the next adventure and the players have been happy to participate so far. I figure if they get into an adventure they're not keen on, they will be able to leave, however the end result will be felt in the world. My game is a modern-day monster hunting one, though I think applying the same philosophy would work elsewhere.

[Altair_the_Vexed]

It really depends on what we're doing - a short one off, or a longer series will be different and need different approaches.

For a one-off, I tend to come up with a reason to have climax showdown, then work backward to set it up. I find that for a single session we can only usually fit in a couple of encounters, and use the rest of the time for scene setting and build up.

For example:
The murder of a priest by some peasants has haunted an area, drawing evil spirits in to feed off the guilt and fear of the locals - the hidden remains of the dead priest must be recovered and laid to rest, but they are guarded / haunted by undead monsters.
Showdown = fighting some undead
Set up = fearful NPC peasants and villagers alert the PCs to the scary undead - but also (with appropriate social skill checks) the PCs get hints about the murder; spooky locations and minor encounters

For a longer set of sessions, I will invent some adversary with a plan, and then work out how the PCs can interact with that plan. To be honest, I tend to follow the Alexandrian's method (http://thealexandrian.net/wordpress/7949/roleplaying-games/node-based-scenario-design-part-1-the-plotted-approach) here.

[Pleh]

I usually do my adventures one session at a time. For this, I like to start by picking a theme to aim for.

Am I wanting to construct a high paced chase?

A methodical dungeon crawl?

A gladitorial arena/battlefield for instant combat action?

A mysterious puzzle with clues?

A map or maze to be explored?

A social encounter with politics and intrigue?

A disturbing horror to be discovered?

These themes tell me what needs to be prepared. A chase needs skill DCs and a convoluted map, but complex at a large scale rather than a small one. Dungeon crawls need a small mix of everything. Arenas and battlefields need to be mostly open, personal scale, but filled with just enough terrain to present tactical challenges and opportunities. Puzzles need a small space with tons of detail so the real clues can be hidden in a pile of useless trivia. Etc.

[Thrudd]

Depends entirely on the game system. Not all work with the same structure. Since the default assumption here is D&D or PF, I'll go with that.

You have something the players want to obtain or a specific goal to achieve. You have a place where they need to go to do that. That place (aka the dungeon) is designed in great detail. The creatures and people that will be there are given habits and motivations and methods of behavior. There are obstacles and points where multiple paths can be taken and decisions need to be made. You have an idea how things may react to different actions of the players, but you're ready to improvise as well, having a strong grasp on the location and its inhabitants.

How they get to the adventure location may be dictated by the style of game you've established. It is not out of the question simply to place the players at the location and tell them what they are there to find or do- if they know this is the sort of game you are running.

I start with them in civilization, and let them seek out rumors of treasure or people with "jobs" or quests, depending on the tone of the game. They learn where one or more adventure locales are (or get a good idea at least), get some idea what to expect there(usually vague and imprecise ) and can then decide how to prepare their expedition. The game is on, and from there it relies on my maps of the world and encounter tables and weather tables and the notes about what creatures and people live in the places they go.

After they do things, return with treasure or whatever, people react to them and they form relationships and get reputations. They learn about more stuff and go on more adventures. Sometimes hanging threads from earlier adventures inspire a later one, or pop up when it seems appropriate or the dice give me a result that fits- remember that guy you killed? This new band of bandits is led by his brother- that"s why they immediately hated and attacked you!(which is a thing the dice told me).