I've been thinking about different structures for encounter tables.

Highest & Lowest

Roll 2D6 and check the highest and lowest scores:

Highest	Encounter	Lowest	Reaction	No.
6	Military Unit	6	Ignore	1D6 x 20
5	Adventurers	5	Neutral	1D6
4	Giant	4	Attack!	1D6
3	Elves	3	Stalk	2D6
2	Trader	2	Friendly	2D6
1	Deer	1	Flees	2D6

• Deer are encountered when the highest number is 1. This makes them rare, and they only have one reaction: run!
• Traders are uncommon out here, but twice as common than deer. They may flee, or be friendly.
• Elves may be friendly, skittish, or simply stalk the PCs for a while, observing them.
• Military units have en equal chance to do anything.

Each creature can gain any reaction on its own number or lower, so the chart assigns certain reactions to certain creatures.

Sample Results

• (1,6): A military unit's scouts assume the PCs are part of a larger force, then return with an exaggerated report, and all forty soldiers flee.
• (5,6): Another unit of forty arrives from a new direction. The PCs can ask them questions, but they don't take much interest.
• (1,5): A fellow adventurer (and sole survivor after a tomb-raiding) spots the PCs and immediately hides in case they're violent.
• (2,3): Six elves greet the PCs, and ask why there are so many military units around.

Introduction & Reveal

If an encounter might hold mystery, and develop over time, but also repeat, then the 'reveal' has to change some of the time.

Sight	Meaning
1 - 3	1. Both alcoholics. They insult each other for an hour and go home.
Two men, ready to fight.	2. A noble, annoyed at the insult from a fisherman, shouts, then instigates a duel to the death.
	3. Two nobles, both want to marry countess.
4 - 6	4. They grow tall once planted, but the actual beans taste bad so he considers them cursed.
Magic bean seller.	5. Standard con-man.
	6. Excellent con-man. The PCs encounter two more people trying to use their 'magic beans'. They will pay money for the con-man's head.
7 - 9	7. This military parade should spread the word: nobody wants to mess with this city.
A massive crowd, march in unison.	8. The people are near revolt! Roll this again, and a riot breaks out.
	9. A religious festival is underway with uniforms, and pikes. As is tradition.

This area has plenty of cursed magical beans which grow tall, so farmers sell them cheaply. This only happens every couple of months, so con-men try to sell fake beans, relying on the various stories to stoke interest and credibility.

Monty Haul Doors

Entering the castle's window, the long, dim, hallway has many doors. Which do you check?

Rather than stocking an entire castle, it seems easier to list some rooms and roll for random contents. But we can't repeat the rooms; instead, we can mark them off and use the next number.

• 1: King, bathing (shrieks for guards).: no
• 2: Man in library, shouting at his son that he must read better. He ignores everyone else.: yes
• 3: Two maids work quietly, deep inside linen closet. They will want to ask the characters their identity, and won't leave them alone until they can badger someone else.: no
• 4: Jester in the privy, taking a pipe-break.: yes
• 5: 'Light pantry' (with candles, oils, and lanterns).: yes
• 6: The librarian, laying in bed.: no

Rolling 2, 4, 4, the PCs open rooms 2, 4, 5 (because room 4 was already open).

If the encounter had just said 'roll until you get a "6"' then they could easily have made 10 rolls and found half a dozen jesters in half a dozen privies.

PCs might also listen at doors, but will have to be fast about it! Every 1D6 rounds a door opens (roll 1D6 to find out which room, including repeats).

Rolling 2, 5: 'in 2 rounds, a butler comes to take candles from the light pantry'.

Rolling 1, 2: 'in 1 round, the father storms out of the library, leaving his son to read alone'.

Groundskeepers & the Garden

The dryads are getting pissed off with people stealing from their garden. Maybe just one more apple?

This enchanted garden has all manner of magical fruit. But the more people take, the less there is to take, and the more local dryads arrive to shoe the characters away.

Roll	First Encounter	Default Encounter
1	Healing Apples	Dryad casts spells from afar
2	Mana-Regenerating Berries	Elven Enchanter enchants PCs to leave
3	Wellspring of Vitality	Human corpse in brambles
4	Mage-Oak Tree	Elven cat smiles and turns invisible
5	Raspberries of Sex-Appeal	Dryad summons bears and wolves

It begins all nice:

1, 4: you find regenerative apples, and in the distance spy mage-oak, capable of making a powerful magical staff.

But each roll becomes more dangerous:

3, 1: you find a well-spring, and it smells fresh. But storm clouds are gathering above, fast.

On the first encounter roll, place the magical plant on the map (each one remains there). Eventually, the map might have six magical plants. But by that time, vicious dryads encircle the area.

Gatekeepers & the Necropolis

The opposite of the above could be used, where the PCs find undead in every tomb in the necropolis, guarding hordes of jewels and gold. But with enough time, they can uncover the tomb's treasures, and flee, perhaps taking one stash, perhaps 'clearing' the lot and finding all the treasure after re-deading all the undead.

Rolling in the Open

Why do GMs roll for random weather behind a screen? Is the possibility of 'light rain' a secret?

I've started adding rolls for animals. Most are benign, but every so often, a dog will steal food, or a cat will just scratch someone. The reaction rolls sit right under the statblocks, so players can roll for their own animals. They don't know exactly how the animal will behave, but they soon figure out how it might behave.

Factions & Regeneration

Random encounter tables tend to be static, but we can make them more interactive in long-term campaigns by removing an encounter once it dies, and replacing it from items in a hidden list. The tables might begin like this:

1. Combine next two encounters
2. Big spider
3. Basilisk
4. Stirges
5. Dryad of the Bountiful Garden
6. 5 of Devon's Boys

The session has encounters 5, 5, 2, and the party end up on bad terms with a dryad and kill her. The next encounter is empty (she's dead), and the third is a 'big spider' (which also dies).

Before the next session, the GM regenerates the entries:

1. Wandering Monsters
   1. Big spider
   2. Basilisk
   3. Stirge swarm
2. Fae of the Bountiful Garden
   1. Dryad
   2. Elven Enchanter
   3. Gnomish Illusionist
3. Adventurers from Vagabond Keep (2D6)
   1. Devon's Boys
   2. The Cartography Cult
   3. The Urchin Squad

• 3, 3
• 3, 1

The new list looks like this:

1. Combine next two encounters
2. 8 members of the Urchin Squad
3. Basilisk
4. Stirges
5. 9 of Devon's Boys
6. 5 of Devon's Boys

If the PCs make an alliance with one faction, the chart will retain them, but lose others. Number 1 can never be removed, but it will change over time.

PS: I just found the I Cast Light blog has the same idea, with a different procedure:

Random Encounter Tables as Adventure RAM