Another one of those common topics of discussion on independent gaming forums involves the concept of shared imagination space, or shared imagined space, or simply SIS. I’ve heard a dozen interpretation of what this actually is, but the concept I like the best is like a communal daydream where everyone adds something into it, and everyone else reacts to the addition. Three types of contributors add to the communal daydream, the GM who sets the stage, the players who act through their players within the setting and the game mechanisms which often impose a level of coherency or apply genre specific physics to the situation.
All of these forces are pulling at the SIS, the GM is often trying to pull the story toward a predetermined goal, the players are typically pulling the SIS in a way to highlight the advantages and strengths of their characters, the system often works to stop players or GM from gaining absolute control over events, thus turning the story into a game experience.
With these forces pulling in different ways, the SIS is pulled tight like the mat on a trampoline. It has a certain degree of give, but if things get too tense it becomes a fragile thing that can easily be broken. If you’ve been roleplaying long enough, you’ve probably seen this. One player pulls in a direction opposing another player, it starts with each believing a different version of a specific event, and as they are unwilling to back down, they continue to interpret new events in ways that reinforce their belief about the storyline…until eventually the two stories become incompatible and the SIS literally tears apart, destroying the game in the process.
In another situation, the players engage in an action that isn’t quite covered by the game’s rules, so a new rule is devised ad hoc (perhaps by the GM, perhaps by consensus of the group). With another situation and another ad hoc change of the rules the story drifts away from the rules as they are written in the book. Some players might realise this and simply think that this is just the GMs play style, perhaps they give it a name like “drift” because they are gradually drifting away from the rules as written and are developing their own evolution of the game more suited to their style of play. Eventually the players realise that they are actually playing a brand new game completely separate from the book where everything started.
Anything can cause a degree of tension that rends the SIS; at first it might be unnoticed, but eventually it becomes obvious and destroys a game. Not all games end this way, some games might walk a fine line, where nothing gains enough strength to cause this damage to the SIS, or maybe the storyline resolves and the game ends before things get too out of hand.
If you’re planning to run a long term game, it makes sense to give the SIS a bit more strength. Make it a bit more resistant to those pulling effects. If all the players and the GM are sharing the same ideas about where the story is going, what has happened and how the environment around them works, then there is a lower likelihood that they’ll pull in mutually incompatible directions. (Don’t get me wrong, there will still be friction between characters, that’s all a part of roleplaying, but now the players should be aware of what they are doing to the story rather than simply pulling at it without understanding the results of their actions.)
There are some easy ways to reinforce the SIS, but most involve a bit of preparation and some homework on the part of the players.
Find a movie that’s similar to the setting you’re trying to portray, or a TV series. If it’s something that most members of the group are already familiar with then you don’t need to sit and watch it again.
If your game idea sits somewhere between two or three movies, get everyone to sit and watch them all…taking notes along the way. Or even take the opportunity for everyone to pick a movie within a specific genre…action movies, sci-fi movies, road movies, post apocalypse…once everyone has picked a movie, everyone should write notes, picking half a dozen aspects from each movie, then discussing their choices during the credits, or before the next movie starts. Once all the movies have been watched, consider which elements are common to them. For example, if you’re going sci-fi and one person picks “Blade Runner” while someone else picks “Alien”, then there is a common thread of very human looking androids, and another common thread of crude space travel with an exodus from the earth. Choose a few of these common elements, and define them as immutable truths about the game setting. Choose a few of the characters as archetypes for NPCs. Limit the weaponry in the game to items that are specifically seen in the films. If you see an action occur in a few of the movies, then it should be pretty easy to accomplish in the game; conversely if you deviate beyond what you see in any of the movies then things would get more difficult.
In this way, everyone gets on the same page about what can be done easily, what should become harder in the game, and what just shouldn’t be possible at all.
You could do the same with books, but this would be a bit harder. It takes a lot longer and a bit more effort to read a book than watch a movie.
Once everyone has the same starting point for a game, and they understand where the boundaries of the imagined world exist, then they can explore the space within those boundaries instead of trying to test the edges and pull the game apart.
That’s the theory anyway.