Making the Instant Adventure
To do an evening – or afternoon – of adventure, you need to have a few things. You need a beginning, a sense of what's at stake, an enemy, and an ending. At the very least you need these four. And if you wish to do a little better, you also need colour, an ally, and a twist. All you need is an idea of each of these things, and you can make up the rest on the spot. Just be consistent.
For the beginning it is important that you get the player characters together. To work together, to basically like or at least tolerate each other, and if possible to stay physically in the same group – most of the time. One way to do this is to let them be invited by someone who asks their favour – a patron. He or she can explain what's at stake – or what the mission is, and propell the adventure forward. The patron may also be one of the player characters. In practice that can work quite well, because you have a player who will help you keep the group aligned.
Another good way to begin is to throw the characters into the action. They are in the mission already, or they are drawn in because the stakes unfold before their eyes. A princess may be kidnapped in front of them, or you may tell them that they are guarding a caravan, or on the way to convince an enemy Duke not to attack their home country – and now his troops try to capture them. Action has the advantage of drawing the attention of the players, and thus you gain momentum in your game.
What's at Stake
You must know what the adventure is about. Is it about honour of the clan, the lost treasure of an ancient king, saving the lives of friends or fellow citizens, or what? This is what the players have to fight for to “win” the adventure. Make it as concrete as possible. And if you can try to hook the stakes to the personal history of each of the player characters.
The enemy is the person, entity, force of nature, army or monster – or any combination thereof – that tries to take that what's at stake away from the adventurers. These are the creatures and forces that will provide combat encounters, nasty face downs, dangerous situations, treacherous conversations and dazzling chases. The master enemy should have statistics and quirks like a player character. Make them up on the spot if you have no time. Or if you're lazy, pick an old enemy. These often even work better.
Every session needs an ending. Not just every adventure, but every session – a good ending is often a reason to come back the next time. A typical ending involves a showdown with the enemy. Or a chase after the enemy. Or a running away from the enemy, or the forces of nature, while trying to save what's at stake. An ending is a climax in a way. And if you can, stage it in a special location, such as on a cliff, in a throne room, or a dragons lair. Make sure you start the ending scene (or scenes) about an hour before you have to wrap up the session. And if your heroes aren't even close to ending the adventure by then, make an intermediate ending, with a cliffhanger. One where an enemy escapes, for example.
So, now you have the main four ingredients, give it a try. Wing it! Next time I'll deal with the other three: colour, ally and twist.