In Medias Res is a Latin term meaning into the middle of things, and it does exactly what it says on the tin. Instead of starting at the beginning, start in the middle (or even the end.)
As mentioned it's a common enough technique in books and movies. Star Wars (the original one) has the famous opening of the star destroyer attacking Princess Leia's ship. Memento begins with what could be considered the ending (note people narrating stuff to another and recalling a story isn't In Medias Res.) Master and Commander takes the technique to the extreme and only gives you the middle of the story full stop, with the film not resolving the entire plot and starting just as a naval battle breaks out.
So how can this be used by a GM? I'm sure most of us have already used it on several occasions sometimes without really realizing it. Simply begin in the middle.
Players are a savvy lot, and like to think they're in control (GMs who let the players actually be in control raise your hand. No, didn't think so.) As a result they will want to know how they ended up in the situation they are in. There are three usual ways of dealing with this
- Fill in the backstory with narrative
- Flashback and let the players control the actions leading up to this by running the game in a different order to the usual linear gameplay
- Make finding that out the entire point of the adventure
Option 1 is the least satisfying for the players as it removes their sense of control and their freedom of choice. Some players may well welcome the skipping of the boring lead up to adventure, but others may not like it. You need to figure out what works with your group before deciding upon this idea.
Option 2 is one I like. You can still run your adventure relatively normally, just the scenes are out of order. The main issue with this one is that unless your players are extremely co-operatives in setting things themselves to allow for the later scene to come true you may find yourself having to railroad some of the choices and paths. Of course the point of the adventure could well be that the future cannot be changed, even if you know of it, in which case creative GMing and running of the world is quite justified.
Option 3 isn't one you can use often. For example the players wake up in a sticky situation with no memory of how they got to be there. They're clones waking up from having memories injected and don't know they're clones. They've been arrested for crimes they don't recall committing and perhaps have been set up and drugged. Obviously there is a limit to how many times this can be pulled off, generally only once per campaign unless it's a long one. In fact often times this can be used as the initial adventure of a campaign where the point is to resolve what happened before.
I've used all these options before on various ways to various degrees of success.
The fill in the backstory with a narrative can be unsatisfying for a player, however West End Games made this work for adventure after adventure when they published their Star Wars Roleplaying Game. The way they solved it was to give out a script at the beginning of each adventure and have each player read a part. This would explain how they got to where they are, and usually would launch straight into the adventure. A famous one I recall was the end of the script running straight into their automated shuttle being flown at high speed straight towards the oceans of Mon Calamari with no chance of survival unless they acted immediately.
The out of sequence gaming one I've used a few times. One of the best ones I pulled off was in a Legend of the Five Rings campaign where I started one of the players off in the middle of a duel. In L5R a duel is conducted by each side taking turns to announce if they'll continue to focus, or try and strike. Each focus increases the difficulty of the hit, whereas a strike announcement will allow the other side to take first hit. The trick is to increase the target number to where you think the opponent will not be able to hit before then flinching.
Anyway I opened the game by asking the player whether he wanted to Focus or Strike and only giving him a sentence of what he sees around him. After he declared then I'd jump the game back in time and start the adventure. After each scene I'd jump back to the duel, give a bit more description of what is happening in the here and now, declare the opponent is focusing, ask the player for their option (it was focus as it always is in the early stages of a duel) and then skip back in time again. Each previous scene would advance things towards what is happening with the duel occurring and generally alter the players perception of the person they were facing. I would try and change the perceptions continuously until it got to the point where the past caught up to the present and the duel was resolved. The end of the duel marked the end of the session with a follow up the following week. I got good compliments from my players for that one.
I've always wanted to try this one as well with the players starting off defending themselves against an accusation in court, and each time the players took the stand they would give their answers to the prosecution's questions by playing out the scene. I'll have to give that a try some time.
Finally for option 3 I ran a Cyberpunk campaign once with the players waking up in a police prisoner transport after having been arrested for the murder of the mayor of Night City. The transport then crashed and the players were able to flee. None of them knew each other beforehand, and I had them do their characters up separately. The campaign was then based around figuring out what happened before (they were obviously drugged, but there was video and eyewitness evidence to the crime) and clearing their name.
So next time you write an adventure, just skip to the chase and start In Medias Res.