The Tension Mounts
In a horror game like Call of Cthulhu the atmosphere is the greatest tool that a keeper has to create a good scary game session. Since Call of Cthulhu tends to focus more on the story being told than the heroic advancement of individual characters it is important to give the players an engaging atmosphere that they remember rather than items of power and experience for the next session. There are physical tools to provide some of this for you however there is nothing more important than giving the players a descriptive and vibrant world in which to ply their trade. An obvious addition to a gaming session is sound. Background music and possibly atmospheric background sound, like a storm, ocean waves or wind can really set the mood. Props are also a good way to give the players a feeling of attachment to the story. Newspaper clippings that are in real newsprint to hold as they read them or possibly a mocked up photograph that the players can pass around are great props that can give the players the feeling that they themselves are taking part in the story and allow them to immerse themselves into their characters.
Sounds and physical props are great but that is only going to get you so far in a game session. Providing tension to your session is not always easy especially when you have players who are joking around and talking out of character a lot. I am not going to discus ways to solve the situations mentioned but as a keeper you should already be pretty good at getting your players back on task. One quick suggestion on bringing the tension to a group that is talking and joking out of character is to give them two quick pieces of information, the first being mundane and the second being important or being something that the characters must react to. The first piece of information can be missed but the players will notice you are talking about in game facts, the second will be perceived by virtue of getting their attention from the first. For example, the players are entering a dark room with their flashlights trained into the darkness. Someone tells a quick joke about the last time they entered a dark room in this fashion. Everyone is laughing and having a good time. The keeper suddenly says your flashlight passes over a figure crouching in the dark corner. "What" some of the players are saying, the keeper then quickly says "The figure moves out of the light and scurries across the floor to the far end of the room". Suddenly everyone is either interested in what is happening or at least telling the rest of the group to quiet down so they can hear what is happening. This works for me most of the time and it gets everyone back on track.
Now that the players are back in focus on the game we can begin to build the tension of the scene. One thing that I use quite a bit is dramatic pausing. So in our example some figure has now moved out of the light and off to a deeper part of the room. Everyone is asking questions now, "What was that", "Was it a person", "Which way did it go", "What did it look like". At this point I like to let them stew for a few moments and say nothing, then slowly bring in some subtle detail, like a sound they hear or a feeling. "You hear singing coming from the far left corner of the room, very low but audible singing". Then hold their attention with repetition of the sound a few times, do it a few times more than you would want to normally, lulling them into a sense that the sound is the key to focus on, at this point hit them with the reveal. When you explain the reveal make sure to do so in rapid succession to give the impression of a situation unfolding quickly and instilling the urgency to make quick actions. For example if we are using the singing example come up with a little tune that you are singing over and over. Let it go over and over a bit too long, suddenly call out several actions in succession. "You feel a rush of wind coming towards you, a figure is revealed in beam of your flashlight, you see a face before you, player X is knocked to the floor!"… "what do you do". What I am usually looking for here is a jump scare, its always fun to have your players jump or call out when they are startled. I may be evil but if I can get one or two jump scares in a scenario I feel like I am doing a good job. The key is to lull the players into a false sense of security in knowing what is coming next by giving them repetition, singing the song over and over makes them believe the line of the song is coming again when you change it up quickly it has a startling or jarring effect. It doesn't have to be a sound being repeated however it could be an explanation of scenery or the description of what someone is doing. As long as you lead them down a path that seems to be the focus then pull the rug out from under them and come at them with something different. The jump scare is great but you can't use it too often or it will lose its impact.
Another technique that I use quite often is time-based tension. Setup a situation where it is clear that something will happen soon, preferably something undesired like the monster will show up, the person whose house your are breaking into will be home soon, anything that has a negative consequence. Then create a task that takes a prescribed amount of time and ends with some skill roll. State that the task at hand will take X amount of time to complete. Then begin to make the player roll a series of luck, or some other rolls that they will begin to perceive as the roll that brings the undesired consequence. If they make all the rolls then have them make the final skill roll to complete the task, if they do they have succeeded and can move on. If however they fail they either begin again or abandon the task. The repeated rolls will in fact bring the undesired consequence, which the players probably have figured out, and so as time goes on each roll brings more tension. A quick example would be this. "You attempt to open the mechanical safe in the cult leaders office, you can do that however it will take an hour for you to complete your task and require a successful mechanical repair roll." "OK, we do that" "OK, 15 minutes have passed give me a party luck roll", "passed", "Another 15 minutes pass give me a party luck roll", "passed, oh man this guys going to come back while we are here, hurry up and get that thing open", "Another 15 minutes pass give me a party luck roll", "Oh no we better make this roll, passed we have to hurry", "Another 15 minutes pass make me another party luck roll", "Oh no here we go, passed, thank goodness", "make me a mechanical repair roll", "failed, oh man lets get out of here before we get caught". Time based tension is great because it gets the players cheering for each other to accomplish the task and if they succeed it gives a feeling of relief and accomplishment.
My personal favorite is what I call the unknown tension. We establish that there is something in a location that is very dangerous and very stealthy. It is impossible to know if this thing is currently at the location or if it is elsewhere. Since we have no way to confirm its whereabouts we can assume that it is in the same location as the players. Now our reluctant hero's have to investigate the abandoned warehouse full well knowing that this is the last known location of the thing. They roam from room to room expecting the worst as each door opens. At this point you have your players right where you want them. If the thing is actually here, well then we will eventually find it or it will find us. If it is not here the players don't know so will assume that it is. Any sound, movement from a dark corner, wind blowing through will now set the players off into a frenzy of panic and if you time your reveal right you can get a good quality jump scare out of this as well. Fear of the unknown is more powerful than something you can see and evaluate. This is the basis of most Call of Cthulhu scenarios so play up the unknown and keep up the tension as much as possible.
Isolation is another great way to create tension in your games. It is always good to isolate the players from the rest of society and any mundane systems of help and protection. Since Call of Cthulhu deals with fantastic creatures and situations you already have a bit of isolation from society available from the beginning. The players can't just tell others what they have seen for risk of being committed. This removes them from society and puts them on an island to themselves. It is important to continue to further isolate your players by either environment "there is a storm and the roads are out" actions "you are illegally trespassing in the old mansion so you can't call the police" circumstance "your in the basement, the thing is in the house above you, you see someone walking down the street above through the small cellar window, but if you call out the thing will find you" location "There is no electricity or phones in this old cabin". Whatever the case may be the more isolated the players are the more tension this will create. There are no avenues to get help and so they are on their own.
There are many ways to create tension in a game much more than I've presented here but I have tried to provide a few that can be achieved easily with the game mechanics. Keeping the players tense and on their toes makes for a truly intense game session that your players will not soon forget. Remember in Call of Cthulhu the story is the important part, creating a good amount of tension will drive that story to its horrible conclusion and along the way create memorable player interactions which wont soon be forgotten. I hope these techniques are useful to Keepers, or at least entertaining to read about. I am sure that the many great Keepers of Arcane Lore have multitudes of ways to create tension and fear in their scenarios, I'd love to hear from you.