This answer is a bit broader than the call of your question but I’ve presented it in this way because in my experience secondary interactions in the game world should always be tied back to player actions.
I’m currently running a Star Wars: Edge of the Empire campaign in which the world being constantly in motion is extremely important. I also can’t devote much prep time for our weekly sessions. So my prep is built around determining what to focus on and when to make it visible to the players.
Focus on the Theme
Whatever game you’re running, there’s a central theme to your campaign. For example, in our EotE campaign, the PCs are trying to rise up from their origins on the streets of Savroia to become wealthy and powerful criminal overlords. If you discussed it up front as you were starting the campaign, everyone knows the theme. But even if it hasn’t been made explicit, after a few sessions, the interaction of the obstacles you place in front of the players and their reactions will make it obvious.
The action in the game world should always feed into that theme. Using another EotE example, Imperial forces are now throwing everything they have at a fierce Rebel uprising in Savroia because I wanted to unbalance the player characters and make the world more dangerous as well as provide them opportunities to move up the food chain.
Why are the Rebels fighting so hard on Savroia and why are the Imperials throwing huge resources at defending it? There’s a reason, but I don’t need to know that reason just yet. As the situation plays out, I’ll come up with a rationale that makes sense. But thinking it all through up front takes too much time. I also know I’ll likely come up with a more dramatically appropriate reason later.
Use the Rule of Three
Three key locations, three primary factions, three events – three is the GM’s friend. This doesn’t mean you limit yourself to three of everything, but you focus your attention at any given time in threes. Operating your world in this way works because:
- You can keep track of three of anything in your head.
- Three provides enough variety without bogging you or the players down.
Again from the EotE campaign, three factions I’m tracking at the moment are the Imperial occupation forces, the Rebel uprising, and the PC’s biggest criminal rivals, The Blue Circle.
Even though I know they have a commanding naval officer and a commanding ground commander, and there are doubtless rivalries and perhaps even factions within the Imperial forces, it’s not worth the time to flesh all that out yet, especially if the PCs do something that helps the Rebels boot the Imperials out of Savroia. If I plan all these factions out, it will subtly influence me to point the game in the direction of exploring those factions, which curbs player agency.
The same is true of the Rebels, and for The Blue Circle, I key off the actions of their leader.
The first NPC that I’m tracking at the moment is Weeho the Hark, leader of The Blue Circle, because he wants the PCs dead but is also (like the PCs) aligned with the Rebels. Will he switch allegiance to use the Imperials against the PCs, or will he put his feud aside and work to get the Imperial occupiers out of his part of the city?
There are over a dozen criminal organizations in the city, and Weho’s decisions will influence them. But at the moment I don’t care about that. When the PCs find themselves in an unfamiliar part of the city, they’ll probably encounter another gang. I can determine at that time whether the gang is for or against the Empire based on the dramatic needs of the moment.
The second NPC I’m tracking at the moment is Kell, an Imperial ISB agent who appears to the PCs to be a double agent for the Rebels. She has been a pivotal connection to both the Rebels and the Imperials in the past, and what she tells either of those groups about the PCs will have an impact. So I pay attention to how the PCs treat her, as that will affect how she treats them. I also know where her actual loyalties lie, which makes it easy for me to make her behave in ways that can sometimes confuse the PCs, while maintining an underlying consistency.
The third NPC in the foreground is Jin-Jael, the PC’s boss. She runs the entire Friends of Commerce criminal organization. She has been betrayed by the PCs in the past but knows they’re effective. This is a time when she needs to place effectiveness over loyalty, and in her mind when the time is right and the Battle for Savroia is almost at its conclusion, she’ll get rid of them. So all I need to track for her is how she perceives the overall threat to her organization, and whether she believes the PCs are still a necessary tool.
There are three immediate events I’m tracking in the campaign:
The Monsoon. It’s the middle of monsoon season. The rain is constant, the ground is muddy, everything is wet, and the fighting for control of the city is influenced by this. It also helps with the mood, and I bring it up constantly, just as earlier I brought up the dusty dry heat. Changes in weather are a cheap, effective way of keeping the world in motion, and they affect everything.
The Battle of Savroia. Here I have mapped out in very broad strokes what the Imperials will do and what the Rebels will do. I know where the big fights might take place, though I haven’t determined when they’ll happen. I’ve also determined where each side’s decision points lie. The Imperials will leave Savroia if they lose a capital ship or if the Army legion on the ground is rendered combat ineffective. The Rebels will leave the field if at least two of their key leaders are killed or captured, or if they lose the battle for control of the airspace above Savroia. Of course I keep this information to myself. The battle will keep grinding on unless and until the PCs are involved in something that pushes the Imperials or the Rebels to concede defeat. I actually have no idea if the PCs will stick with the Rebels or turn coat. This approach allows me the latitude to introduce smaller conflicts within the larger battle, and opportunities for the PCs to aid one side or the other, while keeping the story focus on the PCs. What they do needs to matter.
The People of Savroia. As the battle grinds on, how are the common people of the city reacting? At first many supported the Rebels, but if the fighting goes on too long they may long for the order of Imperial control. Do they see the PCs as Robin Hoods who help those in need, or do they see them as corrupt examples of why the old order needs to be toppled? Again, the actions the players make will influence these attitudes and and behavior.
A Few Ripples Will Do
The approach I’ve outlined thus far may seem a bit simplistic. There are obviously more than three major factions, three main PCs, and three events in any game world. But this is really about applying focus at the right time, because if you know what’s going on in the foreground, it’s easy to come up with ripple effects in the background as needed.
For example, what other gangs think of Friends of Commerce, the PC’s gang, only matters if the PCs encounter another gang. If in some part of the city there are gang members who hate Friends of Commerce (or for that matter Weeho the Hark’s gang, The Blue Circle). But if Weeho decides to side with the Empire, he may try to enlist other gangs in wiping out Friends of Commerce. Maybe some gangs who support the Rebels will team up to take on The Blue Circle, but this only matters in that it affects the PCs interactions with Weeho and The Blue Circle. And when I determine which secondary gangs (if any) will be for or against Weeho, it will be in service of the primary drama, which is the PCs conflict with Weeho.
Motivation Trumps Logic
It’s also worthwhile to remember that immersion and verisimilitude isn’t the same thing as logic. The real world moves in nonlinear ways. People of all stripes act irrationally, thinking they’re acting in their best interest. Love, hate, fear, desire – these emotions can explain many of the things we do, and they can explain many of the things that happen in a campaign behind the scenes, which gives you as a GM dramatic license. You can choose to make those irrational factors visible, retain the mystery, or slowly reveal it.
For example, Amahe, one of the NPCs who was in the foreground much earlier in the campaign showed up out of nowhere in a dangerous situation and appeared quite out of place to the PCs. The simple explanation is that she grew up on a boring out of the way planet and wanted excitement. It wasn’t rational for her to be in the middle of a spice deal in Old Town Savroia, but it was believable.
Prep at the End of the Session
This is probably the most useful technique I’ve discovered. I take notes during the session, to do two things:
- Record what the PCs are doing.
- Be ready to shift focus at any time.
For example, when the PCs first encountered Amahe, she was just a cardboard NPC I created on the fly. Young, rich, in Savroia on vacation from a Core World, she just wanted excitement. As the PCs started interacting with her I figured she’d stay in Savroia and, in search of more excitement, would get involved with the Rebellion. So my session note was: Will be secret Rebel next time they meet her
The notes I take to be ready to shift focus are mostly of that type. They help me flesh out NPCs and provide myself an array of choices for subsequent sessions. For example, at the end of a session in which the PCs were trapped in the middle of a Rebel ambush of a Stormtrooper squad, I wound up with several notes along these lines:
- Ambush killed 3 bystanders - locals pissed off
- SGT saved by PCs - he’ll remember the deed
- Rebels were using Imperial weapons - where’d they get ‘em?
- Flow of spice in Old Town will be impacted (more Imp patrols) - what’s the effect?
Then at the end of the session, usually as the players are figuring out what to do with their experience points and discussing what they want the PCs to do next, I answer the questions that appeared in my notes and update my faction, NPC, and event notes:
- Locals in Old Town are now moderately opposed to the Rebels. Could be swayed.
- SGT is RK-3703 (I’d had him as a new NPC in my notes)
- Rebels have been getting weapons from Kell (add to existing NPC notes for Kell that she’s managing smuggling of Imperial weapons to some Rebel cells in Savroia)
- Spice prices double in Old Town, buyers start going to Blue Circle territory. Weeho the Hark’s profits increase and nearby gangs may try to steal some of his ill-gotten credits (add to existing faction notes for The Blue Circle).
I then ask the players what their characters are planning on doing next. This is an episodic campaign, so I combine my notes with their plans and determine which factions, NPCs, and events will be in focus for the next session. Even if one of them has been out of the spotlight for a while, I have been updating notes after each session, so to shift focus all I need to do is review my notes and update as needed. For example, if Amahe is coming back into focus, what is she doing for the Rebels now that the Battle of Savroia is raging? I determine that and it’s easy for me to drop her into the action in a way that fits the dramatic situation.
It’s a Balancing Act
In the end you want to show a living world without devoting too much of your time to it. It’s also worth remembering that an overly-complex world can bore players. If they’re struggling to remember the names of all the factions, or having to refer back to copious notes they made six weeks ago, just so they can figure out how to react to an NPC, the flow of the game will slow and you’ll lose the excitement of being in the moment.
Verisimilitude is not accomplished through explication; an alternate reality is instead revealed in small, often surprising revelations. A little goes a long way.