A procedure for creating investigation scenarios, or Guess-who adventures

Of all the campaigns I've played, I hold Masks of Nyarlathothep highest. And ever since I played it, I've trying to recreate its atmosphere - without success. The primary reason for this is time. Masks' basic structure is simple: there is a number of nodes, there are local mini-adventures at each node, there are also events that point to the next node, and players gain access to local and the global events through clues. Part of the brilliance of Masks is its scale. The clues are usually very straight-forward: you find a match box from a bar so you know that's where you should go, but the bar is in another country and you also have ten other clues pointing in other directions. What to do? So while the structure is simple, the fundamental feeling of investigating relies heavily on the sheer quantity of leads, locations and events. To create a similar campaign would simply take me too much time.

But another reason is that I wouldn't really know how to start. Internet, and to some extent the game books themselves, is full of advice for creating locations in general, and dungeons and encounters in particular. Other forms of adventures, barring the story-structured adventure, gets much less attention. This is reasonable, since the encounter and the dungeon are widely used adventure building blocks. But this also presents the strange situation where you are given most advice on the things you are already most familiar with. For investigation adventures, you're left with stuff like the three clue rule and that murderers need motivation. And while decent advice, it isn't really helping me. The combined takeaway is that I need three times as many clues, which triples the workload, and need to write some backstory. In other words, I was told to do more of things I already knew I had to do, instead of a different approach to the problem.

So in case your situation is anything like mine, I want to propose a design for creating investigation-centered adventures based on the kid's game "Guess who?". In this design, player-characters are presented with a number of possibilities, and tasked with selecting the correct one. Every step of the investigation leads them closer to zeroing in on the correct solution by eliminating some possibilities, until only the correct one remains.

Below is a procedure for creating such an adventure.

Guess-who adventures

1. Decide on the premise.

The guess-who investigation can only reduce the number of possibilities, never add. This presents a limit to what can be investigated, since there must be some initial separation between possible and impossible cases. Good premises are:
- something is stolen, and only a select group of people knew its location
- a murder on an isolated island
- the gates to the lost dwarven city can only be opened with the correct sequence of runes, but the wrong sequence will flood it with poison gas and seal it off for another century
- have three attempts to enter the PIN code that will open the terrorist's cell phone, and time is running short
- Professor Carlisle disappeared while visiting five ancient cities, where did he go?
- The Crown of Command must be retrieved from the Lich King's hold, but no-one knows in which of his crypts it is
- The Orcs are gathering in alarming numbers in the forest, and the King don't know where to send his troops to meet them

Deciding on the premise is a big deal, since it has consequences for what types of clues are reasonable and how to find them.

2. Set up the clue matrix.

You can make the number of possibilities as large of small as you like. Here I present the basic matrix for 16 possibilities. This makes it solvable with 4 clues, which I think is reasonable.

Criteria 5 and 6 are not needed, and only included here for the sake of completeness. You can save prep time by cutting them.

If your investigation has a lot more starting complexity, like a four-digit PIN, you need a matrix where many more possibilities are excluded than included in each step.

3. Set elimination criteria

If you look at the matrix, you see 8 YESs in each column. One of these is the correct solution, and the other fall into the same category with regards to some criterion. So what are these criteria? Well, really any characteristic that set some of the cases apart from the rest. By knowing that the correct solution fall into the category sharing this characteristic, we can exclude all cases that don't. Therefore, the criteria or characteristics serve the purpose of ruling out possibilities and thereby excluding some cases.

For a murder or theft relevant criteria could be:
Being blonde, leaving the party early, being out in the rain, being elderly, size 10 shoes, and not having an alibi for 9-10 pm.

For a PIN code or dwarven runes, relevant criteria could be:
the second digit is a 3, being a historical date (puts the first two digits at 00 through 20, assuming western calendar), being a prime number, being a birthday of some relation, the four symbols include a combination of frog, ox, moon & sphere.

For a lost city or invasion, relevant criteria could be:
west of some landmark, by a port, far from any major city, site significant in the some personal vendetta with the Lich King, it begins with an N

Four things are important when setting your criteria
1. That they can reasonably be shared between several cases
2. That they are distinct enough that they can be noted separately
3. That they can be formulated as YES/NO.
4. That they exclude a similar amount of cases.

4. Design your clues

Clues can be found in witness reports, letters, travel logs, e-mails or text messages, footprints, a hair left at the crime scene, and so on. Decide if you want the clues to be obvious or require some further reasoning. An obvious clue would be "I saw two people using the ladder that night". A indirect clue would "Smith is in a wheelchair and Hank is afraid of heights; the crime scene can only be reached by a ladder." People feel smarter when they spot an indirect clue, but they are also trickier to set up.

5. Distribute the clues, as you see fit.

Some final comments

Note that the excluded cases in a column don't have to be similar with regard to the characteristic, they just don't match the criterion. For example, your could have 4 suspects with shoe size 7, 4 with size 8, if the footprints indicate that the burglar was size 10.

The investigation will feel more realistic if the proportion isn't strictly half-half regarding each characteristic. Maybe #2 rules out 10 possibilities, while #3 only rules out 7. However, if you shift the proportions, make sure that no clue becomes totally redundant.

Also, since the case can be solved with any four clues, you only need four clues. Including five or six clues, however, give the players more freedom in their investigation. On the other hand, the stucture doesn't really permit more than six clues if they are all to be equal. If for some reason you want more than six clues, the additional clues need to overlap with your original six. A practical way to do this is to think of criteria that by definition or nature appear together. So the size 10 shoe could also lead us to conclude that the burglar was a man, or tall, or both. Or if the invaders will arrive at to the port city, this could also lead us to conclude that come by boat and that the attack is along the coastline. Strictly speaking, these additional clues are of course redundant, but they can provide the players with more options and make the investigation feel more natural.

House Rules

It's been a while since I posted and I'm struggling with the last pieces of the next adventure. But today is supposedly the last day of the Google+ OSR group, and I felt I wanted to post something to commemorate this occasion. During my time at G+, this group has filled my feed with a constant stream of inspiration and creativity, and led me to discover a wealth of outstanding blogs and creators that I might otherwise have missed.

So, in lieu of a proper post with actual content, I offer my house rules.

The starting idea behind these rules was to provide a sense of weight. This is the reason for using damage reduction instead of AC, and for the size die and ability requirements for equipment. But this reasoning also resulted in two rules that might perhaps be of some interest to others: fatigue, and pressing.

Fatigue basically provides an extended range for critical failures. To not make the book-keeping too burdensome, normal equipment and normal actions do not result in fatigue. Opportunity attacks, wielding heavy weapons - and in my game wearing heavy armor - do. In my game, it's treated as a "mild" critical miss: you become easier to hit and attacks deal more damage to you until your next turn.

Pressing, in turn, is a way of gambling a success on getting another success. After an attack hits, the player can opt to attack again instead of rolling damage. If the second attack is also successful, they score two hits. If not, they lose the first. However, for each time the attack is pressed, fatigue goes up by one. I stole this rule from detect magic where it is more unforgiving, but I scaled it back since I want to keep HP roughly in the same spectrum as ability scores (max 20). If you use standard HP progression, the original rule is probably better.

1p Adventure: House of Thousand Idols

The Rod of Seven Parts for my campaign is no rod, but relics of the Martyr King Severend. So far I've detailed the locations for the torso, the head, and the arm, with the aim of making each location as condensed and "constructed" as I can.

Today's addition is the house of thousand idols. The idea was to design a maze that is simple enough to crack for those so inclined and possible to brute-force in a non-tedious manner. My proposed solution is to use symmetric rooms with many passages and no corridors, and instead make the rooms multi-state. So the trick isn't really "do we find the way", but "do we find the right way".

To emphasize this theme, I put in slow but very deadly enemies that trigger if you don't follow the right way, and a cockatrice that can fly - and so have other movement options than the PCs - and has a petrifying attack that further limits movement.

The adventure will work best if the cockatrice is a beatable but formidable foe so that players prefer avoiding it. If they can easily kill it, the maze feel too static so in that case you might want to introduce some rival adventurers or a mother-cockatrice that arrives in 1d4 turns to maintain some urgency.

10 weather features for wilderness encounters

As mentioned earlier, I've been trying to come up with simple setups and situational rules that make random wilderness encounters more tactically interesting without turning them into elaborate set-pieces. Turns out, the always-excellent Emmy Allen had included several in her Narrative Wargame of Chivalric Medieval Romance. Still, many of these ideas were not mechanically explicit, or included things that are hard to recreate in a game with several players and one referee. So I re-wrote the list to make it more mechanically specific. I've used ICRPG notation, so to use it with another system consider hard/easy to be disadvantage/advantage or bonus/penalty, and target to mean AC/DC/TN or any other number that you need to meet or beat to succeed with your action if you use roll-over, or a number to be added to your die roll if you play roll-under.

Also, if you're new to the series, by "board" I refer to any physical surface or visual aid used to frame and represent the spatial relations of the fictional location where an encounter or similar takes place: grid, battle mat, tabletop, graph paper map, wilderness tile, Legos, chessboard...

source: Aths-Art

Random Weather Conditions (adapted from Dolorous Stroke)

Roll 1d12 (or 1d20, depending on how frequent you want weather conditions to be.)
1. Sunrise. In the raking light of the rising sun, normal actions relying on sight are HARD for characters facing East, but deciphering petroglyphs, magical writing and seeing the invisible is EASY.

2. Sunset. Every other round, target increases by +1 (max +5) as darkness decends.

3. Clearing heavens. Every other round, target is reduced by -1 (min -3) as sun breaks through the overcast skies.

4. Searing heat. Physical actions are HARD for all characters wearing heavy armor (plate, or +5 or more ARMOR).

5. Gale. Perception checks, ranged weapon use is HARD, and orders don't carry far in the wind.

6. Blasting Winds. On a 1d4 timer, all actions become HARD for a round, and any exposed and weak terrain feature has a 1-in-6 chance of falling down.

7. Lightning storm. Divide the board in 6 sectors. On a 1d4 timer lightning strikes, hitting the most standout target in a randomly determined sector for 1d12 damage and automatic knockdown. Factors that make a target stand out:
i. elevation,
ii. height relative to neighboring elements (a Large model near Medium models, a Small near no-one),
iii. metal worn
iv. height
If no-one stands out (for example if everyone throw themselves to the ground), decide at random.

8. Lashing rain. The rain makes the ground slippery and visibility poor. Dexterity, perception and ranged weapon use is HARD.

9. Fog. Line of sight is reduced to 6 squares; beyond that it is impossible to discern friend from foe or even characters from objects. Models and terrain are deployed as markers that are only revealed when a PC is within this range and hidden again once out of range. All markers (including those representing unrevealed terrain) move at a speed of 2 squares during the referee's turn.

10. Biting cold. Fumbles occur on both 1 and 2.

11+. Perfect conditions.

1d8 more wilderness encounter locations

For the first set, see here

Roll 1d8
1. Scarp: A steep but low cliff runs across the board. HARD to climb.

2. Abri: A steep but low cliff runs across the board - half of the distance contains a shallow rock shelter. Character under the abri are hidden to all characters above them but easily cornered by other enemies. The cliff is HARD to climb.

3. Giant's kettles: The bedrock surface is here perforated by 2d4 deep, circular holes.

4. Stormthrows: Dead trees lie scattered here, uprooted and broken by storms or the rage of some unknown Giant.

5. Krum-woods: Battered by relentless winds or beset by some curse, the trees here cower behind each other in uneven lines, bent and swollen like rheumatic pilgrims.

6. Stunted forest: The trees here appear old yet curiously small, as if they sprouted directly to senescence. The vegetation blocks line of sight but only to small or crawling characters.

7. Mound: A large circular mound in the middle of the board. Blocks line of sight, and movement is reduced when going uphill.

8. Forking stream: An icy stream or deep ditch runs across the board, forking at the middle. Jumping across is easy, but on a failed roll the character lands off balance and must forfeit the rest of their movement.

1d8 Random encounter locations

Most of these setups are based on locations in Judarskogen, outside Stockholm

I really like Runehammer's videos on room design. The idea of that series is to present a "room", basically a game board or grid's worth of level design, and highlight why it was set up like it was. This makes a lot of sense if you want to play with minis. Setting up a "room" or board takes more time than not doing it and includes carrying and buying extra stuff. So for it to be worthwhile, it must logically add more gameplay than overhead. Therefore, the craft of setting up a board becomes a key GM tool.

That said, there doesn't seem to be much discussion on this topic outside the aforementioned Youtube channel. Maybe this is because most people don't care about grids, or are happy just crafting cool terrain and don't mind just placing it as scatter. But probably, it is also that people who are good at it make set up their boards so instinctively that they no longer think of it as a skill. But for people who - like me - don't fall into any of the above categories, this is an attempt to continue the discussion.

Where does the encounter play out?

Playing on a grid lets you design encounters with a lot of interesting tactical options, with placement, movement, cover, half-hidden details, &c. But since players are free to go where they want and do what they please, most encounters cannot be planned in any great detail. This can create a weird discrepancy between the elaborate set pieces and improvised or random encounters that have very little detail.

As a remedy, I offer 8 dirt-simple setups that adds a twist to your random wilderness encounters.

The PCs start at one edge of the board, the monsters at another. The winner of the first initiative or surprise check decides who starts where, but each side places its own models.

1d8 random encounter locations
Slippery slope: With every move, a character must also move one sq downhill (two if dashing). Moving uphill requires a DEX roll, on a miss the character must use both hands to hold on: attacks against her are EASY.

Thickets: the path runs like an S between thickets. The thickets block line of sight and are so dense that riding or dashing is impossible, and using long weapons &c is HARD.

Criss-crossing paths: several patches of dense forest vegetation. These copses block line of sight from the outside but not for characters looking out from them.

Dark pond: a small but deep pond in the center of the board, just wide enough to be impossible to jump over.

Erratic Rocks: a field of large moss-covered boulders. The boulders are tall enough that it takes a STR roll to climb and DEX roll to avoid damage if falling, and stand close enough to allow jumping between them.

Moraine wall: uneven rocks form a natural wall across the board . DEX to cross.

Ford: A rapid river downstream a ford, running diagonally across the board. Crossing the river outside the ford requires a STR test, on a failure the character is swept downstream to the pond at the far end of the board.

Leading lines: three pairs of statues stand by the edges of a bog. Each pair indicate a leading line where passage is safe and unhindered; a character stepping more than one square out of the line is stuck and must roll STR to get out (EASY with aid, HARD otherwise).

1d10 bridges

Another set of hidden kingdom-style encounters.

BRIDGES
The path you travel gradually widens to a road, overgrown with weed and rarely used but paved with the rectangular stones of a distant empire. Still, the old bridge surprises you - so stark is the contrast between this landmark and the surrounding wilderness it defiantly rises over. Built by unknown masters it appears at first to have withstood time's wear remarkably well. But as you look closer, an ominous feeling grips you.

If the tower is approached, roll 1d10:

1. The ground has sunk or the river risen, for this low stone bridge is currently two feet below the slow, clear water. In the surrounding reed lives an ancient pike of astonishing proportions. The pike (HD 3, dmg 1d6) lunges out of the water to snatch and drown its prey. Its belly is full of half-digested equipment, including a golden ring of growth (+1 CON, bearer must save or begin to grow).

2. Fallen trees and other debris has piled up against this sturdy bridge, turning it into a dam of sorts. The overflowing water forms a roaring cascade that makes passage perilous.

3. Hundreds of crows have gathered on this bridge, forming a heaving mass of deafening noise and black feathers. Like the lazy pidgeons of a city, they move only reluctantly for passers by.

4. On the far side of this bridge, a knight sits atop his horse still as if sleeping. As soon as anyone sets foot on the bridge he stirs, lowering his lance to charge.

Enchanted Knight: HD 4, Lance (dmg 1d10), Shield (+3) and Sword (dmg 1d8).

5. Scattered across this bridge are the planks, tarps and ropes of a broken cart. Throning on this debris, a golden chalice gleams - curiously clean and standing proudly on its foot.
Hidden under the debris is a great snare, set by a bloated troll that lives under the bridge and used for pulling anyone approaching the chalice into the river below to be suffocated and eaten.

Fishing Troll: Large, HD 2, fillet knife (dmg 1d6, bleeding +1). The fishing troll rerolls HP each round.

6. A section of this bridge is missing, but it appears someone is working on its repair for tools and sawdust litter the bridge and a system of ropes and pulleys secures a gangway hanging suspended over the hole. The gangway is damp and worn and easily rocked, but the sturdy wood supports the weight of a horse.
Four outlaws (HD 1) hide nearby, ready to cut the rope that suspend the gangway and plunder the corpses. At the bottom of the river is 1d10 gold crowns that the outlaws have failed to salvage.

7. At each head of this long bridge is a tower, where a black portcullis blocks passage. An intricate construction allows the them to be lifted one at a time, but only from the opposite bridgehead.
In the far tower rests a raid of harpies, anxious to not let anyone near their plunder. In 1d6 days, they will be gone.

Homebound Harpies: HD 2, flying.

8. A crone has set up shop on this bridge, selling salves and potions and remedies for broken hearts. She is friendly and knowledgeable, but acceppts only the barrowmen's coins.

9. Time has withered down this bridge to the point where it is little more than a moss-covered arc over the busy brook far below. Three ropes dangle from its crest, old but with nooses still intact.

Downstream, the remains of three women can be found along with a silver amulet of the Old Faith (+1 WIS, wear the skin of an animal to learn its tongue). A skinless beast (HD 3) will begin hunting the bearer in 1d6 nights unless the remains are properly buried. However, with a christian burial the amulet's magic wanes after one use.

10. In the middle of the bridge is an enormous ogre, clad in iron and maille it reclines on a heap of plunder and appears to be napping. A large dog rests by its side. Tethered to a large iron pot and a split-open heaume, it produces a terrible noise that will wake the giant if it moves.

Hrud, the half-giant: Giant, HD 6, AC +8 (wrought iron), stone sword (dmg 1d14).
Millud, the hound: HD2, AC +2 (fur), dmg 1d6.