Tension and Suspense?

[Isida Kep'Tukari]

As others have said, foreshadowing.

I'm playing a Forgotten Realms (3.5) game, and early on I planted the idea about Skullport, a sort of underground Tortuga combined with Mos Eisley, as a place of danger, run by monsters and villains. I mostly was doing this for flavor when I was describing the various districts of the city. Then, as the group faced a foe who became a long-time antagonist, I mentioned he had most likely fled to Skullport. Additionally, they had met other short-term villains who had connections to Skullport, usually very, very bad ones (poisons, slaves, other evil doings). All of this built into their paranoia that Skullport was some place they really, really, really didn't want to go.

Then they had to go there.

I used creepy sound effects and creepy description during their time in Skullport, but what the players told me really got them scared about taking their characters down there was the knowledge of how very, very badly things could go if they slipped up. They knew what sort of people were down there, and they knew some of what could happen to them, and they also knew they didn't know the worst of what could happen to them. They knew they couldn't fight their way out, or bribe their way out, or talk their way out (or so they had convinced themselves). And even though they managed to get out in one piece, their skins were still crawling afterward.

So, build up the potential danger early and let the players fuel their own paranoia.

 

[Yora]

Suspense works very similar to fear. And the key to creating it is to put the characters/audience into situations where they are not in control.

The most important thing is that they must not know what exactly they are dealing with.
If you know what a creature or a threat is, then you have a pretty good idea what it can do to you, what it might want to do with you, how you can protect yourself from it, and how it can be defeated.
You may not now what exact stats and abilities a wyvern has in any given game, but when you hear that it's a wyvern, you are probably assuming that it's not very smart, has the ability to fly, a nasty bite, and probably a poisonous spike. Even more so if you know you are dealing with a vampire or a werewolf.
And then, you know what to do. You can't be sure your attempts to defeat it will be successful, but you know what things you should try and which one would surely get you killed.

But if you don't know what you are dealing with, then you're in big trouble. If you don't know what it can do, what it wants, how it will react to things you do, and what things can or can not harm it, then what are you going to do? Anything you try might help you to survive, but it could also be a mistake that gets you killed.
And the fear of doing something that will make things worse without knowing it is a huge source of dread and suspense.
If you know what you are dealing with, you know what you should do, and that means that you are in control and simply should stay calm and focused and do what you need to do. And that's the last thing you want if you want to create suspense.

 

[DungeonsNDads]

I echo DrunkonDuty with barriers.

If they have to get somewhere before a specific time, or before a certain event, or anything where there is a definite "run out of time" then barriers work a treat. I always find starting them off slow, easy to dodge if they wanted to, but the type of things they might waste time on thinking "Oh we have plenty of time". Typically you can do this in the form of sidequests, where they think "We have to get to <city> in 10 days, but helping these clerics will only take us a day out of our way so we'll still have plenty of time"... Creating events that they could ignore, put probably wont.

... throw in a couple of those and suddenly it's a case of "Can we really afford to spend time doing that when we now only have 5 days left to get to <city>?" And this is where the barriers become a little harder to ignore, the children that have been kidnapped or the other large threat that might arise if someone doesn't deal with it there and now. Here you create events that they could ignore, but will find it hard to (for RP/character reasons no doubt).

... then as they draw closer and can feel the noose tightening as they start to run out of time, then you put in barriers they can't avoid. A bridge that is out, that will now force them to either go another day out of their way to take a different bridge, or potentially try to cross the perilous rapids. The bands of orcs that have risen in the countryside that they are traveling through, getting into fights and forcing them to rest or push on injured and with fewer resources. Here we make it extremely difficult to keep pushing on.

Suspense only really works when you are so close to succeeding but could still quite easily fail. A slow build up and then pile on the pressure.