First, let me define some terms that i will use for the rest of my post.
There are a few keys to being able to scare the crap out of your someone through fiction, regardless of context (game, film, book).
First is Horror. As was once described in a Ravenloft setting book, Horror is a reaction to something that while it poses no danger to you, still causes a scary reaction. Finding a dead body is a good example of this. It is not going to get up and attack you (in real life anyway), but your probably not going to be calm about being near a corpse.
Next is Terror. Terror is best described as the feeling that something specific is out to get you. A fear of 'something' around a corner that you cannot see but can hear is terror. Movies that manage to scare you without showing you anything for long periods of time work on this level.
Aside from the two distinct kinds of fear, there are two modifying elements, intensity and tension.
Intensity is self explanitory. Low intensity is easier to acheive than high intensity. Tension is the second. Tension in this context refers to how long you sustain a feeling of Horror or Terror. The more tension you can bulid, the bigger the payoff when you release it. Many horror movies will have a scene where someone hears a noise, and the music will build up as they approach the closet, and discover their cat. Or they will build up and release the tension with a big "Boo" moment which in movies is usually a loud noice followed by something of note happening.
Now, your scenario is a cursed island that corrupts the things on the island. That can be worked with pretty decently.
If you want to build a sense of Horror, you need to establish early on how things on the island are often just wrong in some way. The easiest way to do that is to describe things that simply 'should not be'.
Encounter 1, a battle site.
For starters, the players ought to come upon the site of a battle of some sort. There should be a couple of bodies of the losers, and they should be in very bad shape. Large gaping wounds, bits of people strewn about that require some sorting out. There ought to be signs that there was something large and powerful near the fight. Broken trees, deep foot prints, and weapons and armour that are twisted into unusable shapes. The prints should be unidentifiable. And the bodies after some examination should be your players.
To make this work, describe the bodies of the players in increasing detail as they make skill and search checks. The gear that is found should be broken and unusable, but recognizable as the same kind of gear that the players have. When the players bust out the divinations, note the following:
- Detect Evil should be off the scale
- Divinations will indicate that these are the bodies of the players
- Speak with Dead should result in nothing but screaming from the deceased
- The wounds on the players should be described in graphic detail. Crawling with maggots, covered in strange ooze, and smell like diseased filth
- Inflicting damage on the body parts should cause harm to the corresponding player.
Encounter 2: The settlement
The players should find a medium sized town, and they should find it around mid day. Everything should be in perfectly working order, and in good repair. It should be very clean, and well maintained. Be sure to mention the lovely flower garden and marvelous fountains. There should be white picket fences, hedge sculptures, reasonably fresh paint, and a generally cheerful atmosphere. There should also, under no circumstances be any living thing in the town. Also no undead or monsters. The town is just completely empty. If they search, let them find all sorts of valuables. Be sure to put in a modest magic shop with some decent goodies. Any given shop ought to have plenty of gold. In the homes and in the market place, and food items to be found should be ripe, wholesome, and nourishing. Any meat should be fresh. There will be garbage, but it will be in the expected places and not particularly noxious or suspcious. Under no circumstances should they find any sign that there is anything wrong with the town other than it being completely empty.
If your players are at all sane, the fact that they can loot the town of useful items and money with impunity should make them extraordinarily suspicious. If someone casts a detect evil, it should be blinding.
If they spend the night in the town, feel free to mess with them. I suggest that sometime late in the evening the players end up hearing the sound of every person in the town screaming in pain, agony, and horror until sunrise. The screaming ought to be audible even in a silence spell, making it impossible to sleep. If they stay a 2nd night, just run with it, amping it up.
I also suggest that once the screaming starts, that they find themselves unable to leave the town. Travel in any direction just lets them see more and more of an unending town.
3) NPC Night Terrors
If the players have any henchmen with them, after the first night, the henchmen should be found to have clawed their own eyes out in their sleep, and bitten off and swallowed their own tongue. Do not under any circumstances explain why this happened.
4) Tension builders
Toss in any of these one off elements to help build tension.
- When a player asks to make a listen check, perform the check as normal, but also tell him that he notices his ears are bleeding. No damage, no explanation.
- At some random point, tell the players that something nearby smells like many recently dead but 'ripe' corpses. Let them search, and find nothing. The smell never goes away
- When the players bed down for the night, tell some of them that they wake up in water. Let them spend a few rounds making Fort saves, and look up the drowning rules. Let them make swim checks and tell them there is no land in sight for a while. After either 1 person fails and drowns, or 1 hour worth of checks, or someone disbelieves and makes a DC XX will save (pick the number to be difficult, but allow infinite retries) they wake up in their bed rolls. They are also wet, and have perhaps taken some ability damage. No restful sleep that night.
- If protection from Evil is ever cast, have the protected character illuminated in a dazzling spray of sparks for the duration.
-- If you go with a Cthulhu-esque cosmic horror theme, consider having protection from evil do nothing, and have protection from Chaos be required instead. Allow a Spellcraft or Knowledge(Religion) or Knowledge(Arcana) to have the players discover this after Protection from Evil fails the first time. The first failure should be dramatic.
5) Bizzarre combat
- Upon any suitable gruesome sight or stench, have them roll DC XX fortitude Saves. Just pick a number that the best fort save only succeeds on an 18 or better. Those who fail start to vomit. What they vomit up are either Insect swarms or oozes. They start the combat Nauseated until they succeed a DC YY Fort save (give the worst save a chance to succeed on a 14 or 16 or so).
- Have a half mad 'survivor' run up to the players and beg to be killed. Go for a lvl 2 commoner of middle age, or even a small child. The opponent cannot be subdued by sleep or held or subdual damage. Make it an obvious non threat, and try to force the players to kill it. If they do not kill the opponent, at the first meal opportunity, have him commit suicide in some gruesome fashion, like cutting out his own small intestine and strangling himself. The next day, have them fight the dead persons ghost, still insisting on being killed.
- If a cleric tries to use a Turn undead, have him suffer the effects of his own turning as he is enveloped in a powerful wave of negative energy. If he would destroy himself on his own turning attempt, just drop him to as many low hit points as you care to.
That is all for now, until you give me an idea of what might be considered pushing things too far in your game.
END COMMUNICATION
