I often joke that GMing is one part world-building, one part storytelling, and one part psychological warfare. Hence why July is psychological warfare month, also known as messing with your players for fun and profit. But before I can talk about how to play head games with people to get them more engaged in the game and heighten tension, I need to talk about how this jives with treating people with respect. This isn’t a month about messing about with your players’ triggers or exploiting their vulnerabilities, it’s about managing the game in a way that heightens tension and engagement. With that in mind, let’s talk about psychological warfare and limits.
Because of the trust your players place in you, you’re given a bit of a license to mess with them in the service of the game. You already do this. Maybe you say “There don’t seem to be any traps” instead of “There are no traps.” Maybe you play the Killer GM a bit, and set them up to wrest their achievements from your apparently clutching fingers. You might just sit around and dream up ways to get at the PCs through the players’ payouts rather than what they say their character wants. If Susan can’t resist a fight, then she’s the perfect person to spark a confrontation.
You can do a lot more than that, though. Sometimes I’ll rearrange the seating to make for more or less efficient note passing, or mix it up by adding less comfortable chairs. Lighting can change a lot too, and what you do with yourself can influence people’s reactions. If you play in an open space like a living room rather than around a table, you can move around and get in people’s space. You can drop hints out of game, leave notes out, pass something the wrong way, and use other kinds of misdirection to set them in the mood and direction you want. The more trust they give you, the more you can do.
You’re in control of when and how you do those things. What you’re not in control of is when it stops. If someone gets uncomfortable, back down. This isn’t always easy to tell, so err on the side of caution always. there’s a fine line between “This is interesting and tense” and “This is totally creeping me out in a not good way.” A big part of doing these kinds of things is reading the cues your players are giving you about how they’re feeling, so make sure you’re attentive so you know when it’s too much.
I wish there was some harder advice I could give on this, but everyone is different and responds to different things. I’ve had players who lose it when faced with the killer GM act, some who are really space conscious, and some who get agitated at a major change in routine. This isn’t the kind of stuff you do with strangers at cons or with the gamers down at your local gaming store, this is stuff you do in your regular game with friends, people you have a deeper relationship with and whose trust you’ve earned. You can do a lot with this and be prepared to make some mistakes and do some apologizing. Find the right mix of sensitive and sneaky and your game will definitely profit.