Players can be frustrating. At times, they are paranoid to the point of inaction. Other times they laugh at your best villain. So what’s a surefire villain that will get them unnerved and unsure about their ability to defeat the enemy?
Any enemy that you cannot tell where they are is going to be a difficult one to defeat. Maybe they’re invisible and can move around the players waiting for the best time to strike. A good number of games deal with something along these lines and there are usually countermeasures for invisibility if the setting allows for it. But even this is just a warm up for the scariest enemy.
Even more frightening than an undetectable enemy is one that is supposed to be an ally and there is no way of telling if they are on your side or not, a converted friend. They may have worked along side you for weeks or months, maybe even years but something turns them against you. Especially where anyone can be suddenly converted into an enemy or anyone you’re relying on can be waiting for the right moment to carry out a dastardly plan.
So how can this kind of an enemy be used in a game? How can you make a game that makes even the most experienced PCs shudder in their boots?
The first thing to do is to surround the PCs with people that really are on their side or at least neutral. Any town, city, military base, barracks or well populated space station will do. Something needs to make this place necessary. Maybe the players are there for the safety in numbers, maybe they need to stay there for another reason but that should be well understood and explained in the game. If at any point the players decide to leave make it obvious that leaving is unlikely to be a viable option.
The next thing to do is determine a number of enemies the players will have to deal with that will be hidden in their allies. It could be a single enemy or it could be dozens depending on the player character’s ability. Figure out how the enemy is able to hide in among their allies. This can range from pod people scenarios to sleeper agents planted long ago.
The last thing to do is create a plot that puts everyone in danger. The players will not be able to ferret out the enemy by any means, they must find out how the enemy has planned to put their plot in motion. Only by guessing the plot and heading it off will they be able to prevail and survive.
Any input?