Conversion Guide: Adapting a Mystery
Liminal Horror is not the only investigative horror RPG out there and there are many other settings and scenarios that would be right at home in your campaigns. This chapter will discuss various ways to take the pieces of those games and adapt them to be better suited for this system.
However you are not bound by pre-written scenarios and the specific guides below. Many of your favorite novels, comics, movies, and video games can be harvested for their parts or lifted wholesale with a fresh coat of paint. To bring your favorite pieces of media to life at your table, use the general guidelines below alongside the prior advice in Creating a Mystery (p. x).
General Guidelines
When diving in to prepare to run an adventure not directly written for this system, don’t feel compelled to create a perfect mechanical conversion. These games have different goals and design ideology than Liminal Horror, so a “perfect” conversion might not be an ideal outcome. Instead, the goal should be to capture the themes and narratives without getting too bogged down by the numbers. If you keep the following tips in mind, you’ll likely even be able to convert on the fly.
Selecting Scenarios to Adapt
Liminal Horror isn’t always going to be the perfect system for the scenario you have in mind. However, the scenario does not always need to already have a baseline of horror, as that’s always something that can be added in later. Scenarios that lend themselves nicely to be run with Liminal Horror often include one or more of the following elements:
- A naturally escalating tension.
- A damning secret hidden by facade.
- An agent of change, be that to the setting or its character.
- A setting that could be easily made to feel right at home in our real life.
Genre Shifting
There are many fantasy and sci-fi stories that would make great horror scenarios with just a shift in tone. This will have less to do with changing what is written and more to do with how it’s presented at the table. The shift may be as simple as adding in a source of tension or ramping up the danger, which can be achieved by adding in a Doom Clock (p.x) or Voidcrawl (p.x), or twisting the dangers to be more horrific or targeted towards the Investigators.
Setting Considerations
One of the advantages of roleplaying in the modern era is that your players will already have a basic frame of reference for the environment. For example, you don’t need to describe the intricate details of a corner store, as they likely can already picture what the space is like from having been inside one or having seen them featured in popular media. When adapting a setting dissimilar to our own, save yourself time by swapping out incongruous elements for real-world analogues where possible. An inn on the side of the road could be a run down motel, a fusion reactor could be a boiler room, a stone lookout post could be a firewatch station, etc. It doesn’t need to be a perfect replication of the original as long as the general purpose is similar and logically matches the updated setting.
Framing
Horror is often about the juxtaposition of the mundane against the weird and uncanny. Once you have a basic foundation, lean into the influences of the weird and how those stand in stark contrast to the mundane locations. If the scenario you’re converting doesn’t already have solid clues to spur investigation, this is the framework you start to build upon. Leverage extraplanar incursions, reality warping influence, darkness hidden within forests, and the uncanny nature of forgotten and abandoned places.
Saves or Specific Ability Checks
There will often be situations in a module or supplement that call for a specific skill check or save. Instead of automatically defaulting to replacing them with a STR/DEX/CTRL Save, consider the advice in When to Call for Rolls (p.x). If the result of failure in these situations would be uninteresting or there is potential for players to leverage the tools at their disposal, a roll may not be needed at all. You can often ignore roll prompts entirely by having the player describe their character’s actions and what they hope to achieve, and then determine if a Save would be appropriate.
Stat Blocks
Complex stat blocks are unlikely to be necessary for the vast majority of creatures. Most basic Horrors and NPCs will only need STR, HP, and Damage Die, relying on their narrative aspects to carry the weight. For quick conversion, use the generic stat blocks in Creating Horrors (p.x) as a basis, or find a suitable analogue in Catalog of the Strange (p.x). In general:
- Hit Protection: This is a creature’s ability to avoid serious harm, not a measure of their health or vitality. A creature with a high Hit Protection might be quick, particularly skilled, or have some otherworldly defense. As a baseline, an average person has an HP of 3.
- STR/DEX/CRTL: If a creature is particularly apt at surviving direct hits, give them higher STR. If they are quick and nimble, give them higher DEX. If they understand the weird, or are particularly charming or intelligent, give them a higher CTRL. As a baseline, an average person has a 10 in each stat, with 18 as the maximum any mundane creature could hope to achieve.
- Armor: The typical range is from 0-3 based on the protection they provide from physical damage. Most armor values can just be converted along that scale. 0 is unarmored, 1 is light protection (thick jacket, hazmat suit, leather armor), 2 is medium protection (ballistic vest, chainmail), 3 is heavy protection (full combat armor, bomb suit, plate mail).
- Damage Die: In general, follow the advice in Damage (p.x). Unarmed attacks deal d4 damage. Standard weapons deal d6 damage. Specialized weapons deal d8 damage. Reserve d10+ damage for artifacts, horrifying creatures, or particularly devastating attacks.
Special Abilities & Magic
Transcribing a creature’s special abilities is likely going to be the trickiest part of conversion, as they need to be handled on a case by case basis and the system mechanics may not allow for a direct conversion. As a general basis:
- Focus on preserving key abilities. Combat only ever lasts a few rounds, so creatures will rarely need extensive lists of highly detailed abilities.
- Abilities that cause direct harm should be given a Damage Die, following the advice in Damage (p.x).
- Abilities that are particularly weird or have the potential to elicit change through Fallout should deal Stress.
- Anything that targets the Investigators faculties (impairing vision/hearing, restricting movement, confounding, etc) should require a Save or have a specific trigger.
Sanity
It is fairly common for similar systems to include a Sanity mechanic, signifying a character’s descent into madness after being exposed to horrors not meant for the likes of mankind. Liminal Horror has intentionally diverged away from the concept in an attempt to avoid the problematic aspects associated with the stigmatization of mental health struggles. Therefore, replacing Sanity mechanics will not be a simple one-for-one. Leverage Stress and Fallout as a means to simulate the Investigator’s proximity to the weird.
Using Stress The following guidelines are a good metric for integrating Stress into an adventure:
- 1 Stress: Witnessing something horrid.
- 1d4 Stress: Particularly horrific scenes or the abilities of minor horrors.
- 1d6 Stress: Abilities of major horrors.
- 1d8+ Stress: Abilities of particularly monstrous entities or witnessing events not meant for human eyes.
Fallout
While one of the generic lists available in Appendix XYZ Fallout (p.x) may perfectly slot into your scenario, Fallout is often best when specifically tailored to the themes of the scenario and its horrors. It’s encouraged to review Creating Fallout (p.x) to have a few on hand. Depending on scope, start with 3 or 4 and go from there.
Specific System Notes
Mark of the Odd
Liminal Horror shares a lineage with Into the Odd and its many descendants. As such, many of the adventures for these systems can be used near seamlessly. These include, but are not limited to, Electric Bastionland, Mausritter, and Cairn.
Ability Scores and Stats
Replace WIL or CHA directly with CTRL.
Damage
Damage sources can be used as written. Replace damage from creepy or uncanny abilities with Stress.
B/X Descendents
Basic/Expert D\&D and its retroclones like Old School Essentials and Basic Fantasy RPG. These guidelines should also generally be applicable to anything that labels itself as “OSR compatible”.
Hit Protection
As a basis, start with 3 HP and add an additional +1 for every Hit Die. Adjust as needed.
Armor
Use Leather, Chainmail, and Platemail as reference points. A lower THACO AC means more Armor.
- No Armor (9+) = Armor 0
- Leather (7) = Armor 1
- Chainmail (5) = Armor 2
- Platemail (3) = Armor 3
Ability Scores
Ability scores for Strength and Dexterity can be used directly. For Control, determine if Intellect, Wisdom, or Charisma are more important aspects of a creature and use that score, and adjust up and down based on how likely they are to give into the influence of the weird. Alternatively, Morale (ML) can also be used to roughly determine CTRL. ML 4 8 10 12 CTRL 6 12 15 18
Combat
Damage can be used directly as written in most cases. Use Stat Blocks (p.x) for further advice. Multiple attacks in a B/X statline either uses the Blast tag (damage applied to multiple targets) and or the Dual Weapons (p.x) rule (roll two dice and take the higher of the two).
Saving Throws
- Death or Poison = STR
- Wands = DEX
- Paralysis or Petrification = CTRL or STR
- Breath Attacks = DEX, STR, or an appropriate damage die.
- Spells, Rods or Staves = CTRL
MÖRK BORG
This includes the original Mork Borg as well as its iterations and hacks such as Cy Borg, Frontier Scum, Vast Grimm, and Cthork Borg.
Hit Protection
Divide the creature’s HP in half and adjust as needed. Remember that serious threats have HP 10+.
Ability Scores
Mork Borg is primarily player facing, so there are no direct analogues for the ability scores. For Strength, use the creature’s starting HP as a guideline, though remember that only legendary entities have Ability Scores above 18. For Dexterity, start with a base of 10 and adjust as needed to account for Specials that alter DR while attacking or defending. For Control, use Morale (ML) as the rough basis. ML 4 8 10 12 CTRL 6 12 15 18
Armor
- No Armor = Armor 0
- Light (-d2) = Armor 1
- Medium (-d4) = Armor 2
- Heavy (-d6) = Armor 3
Combat
Damage can be used directly as written in most cases, though note that base weapon attacks in Mork Borg are often a d4 when they’d be a d6 in Liminal Horror. Use Stat Blocks (p.x) for further advice. Multiple attacks either use the Blast tag (damage applied to multiple targets) and or the Dual Weapons (p.x) rule (roll two dice and take the higher of the two).
Call of Cthulhu
Hit Protection
Divide Hit Points by 3 and adjust as needed. Use Size to determine if a creature would be more difficult to hit or harm.
Ability Scores
For Strength and Dexterity, divide their respective analogues by 5. For Control, divide the creature’s Power by 5.
Armor
Use the values below as a point of reference:
- No Armor (0 points) = Armor 0
- Present US Helmet (4) = Armor 1
- Heavy Kevlar Vest (8) = Armor 2
- Body Armor (12) = Armor 3
Movement
Movement in Liminal Horror is standardized, with most creatures able to move about 40 feet on their turn. Instead, use a creature’s Move score to determine if it would have a boost to HP or Dexterity.
Combat
For quick conversion, use equivalent weapons on the Equipment Table (p.x) to determine damage. Otherwise, below is a rough conversion. Ignore damage modifiers when adapting.
- Minor (punch, kick) 1D3 = d4
- Moderate (guns, knives) 1D6 = d6
- Severe (high caliber round, fire, explosions) 1D10 = d8
- Deadly (car going 30 mph, close to an explosion) 2D10 = d10
- Terminal (hit by speeding car, closer to an explosion) 4D10+ = d12
Sanity and Stress
Refer to the prior section on Sanity (p.x) for general guidelines. For quickly replacing Sanity with Stress you can reference the Conversion Table:
Stress Conversion Table CoC LH 0/1D2 = CTRL save or 1 Stress. 0/1D3 = CTRL save or 1 Stress 0/1D4 = CTRL save or 1 Stress 1/1D4+1 = 1 Stress 0/1D6 = 1d4 Stress 1/1D6+1 = 1d4 Stress 0/1D10 = 1d6 Stress 1/1D10 = 1d6 Stress 2/2D10+1 = 1d6 Stress 1D10/1D100 = 1d8+ Stress
Delta Green
Hit Protection
Divide Hit Points by 3 and adjust as needed. Use any relevant Defensive Qualities for unnatural threats to determine if a creature would be more difficult to hit or harm.
Ability Scores
For Strength and Dexterity, use the Score for the respective analogues. For Control, use the creature’s Power Score. For creatures with Scores that exceed 20, cap at 18 for more mundane entities. Eldritch creatures either have Ability Scores of 19-20 or are powerful beyond measurement through traditional stats.
Armor
Use the values below as a point of reference:
- Kevlar Vest (3) = Armor 1
- Tactical body armor (5) = Armor 2
- Wall or light vehicle armor (10) = Armor 3
Combat
For quick conversion, use equivalent weapons on the Equipment Table (p.x) to determine damage. Otherwise, below is a rough conversion. Ignore damage modifiers when adapting.
- Minor (punch, kick) 1D4 = d4
- Moderate (guns, knives, baseball bat) 1D6 & 1D8 = d6
- Severe (rifles, shotguns, small explosives) 1D10 & 2D6 = d8
- Deadly (car going 30 mph, explosions) 1D12 & 2D8 = d10
- Terminal (hit by speeding car, IED, artillery) Lethality 20% or above = d12
Combat Maneuvers
For a more tactical experience that integrates combat maneuvers, use Appendix Tactical Combat (p.x).
Sanity and Stress
Review the prior guidance in Stress (p.x). For quick conversion, references to Sanity loss convert instead to Stress Damage. For a Sanity loss of (x/1Dx), have the Investigator make a CTRL save. On a success they take the first number (often 0), and on a failure they take the resulting Stress (using the dice indicated). Critical Stress results in Fallout (p. x).
Monster of the Week
Doom Clock
The Countdown can be directly ported to a six step Doom Clock.
Hit Protection
Divide the Harm Capacity by 2.
Ability Scores
Creatures in MotW do not have traditional Ability Scores. Use the generic stat blocks in Creating Horrors (p.x) as a basis or find a suitable analogue in Catalog of the Strange (p.x).
Armor
Use as listed.
Combat
Use the amount of Harm a Wound can cause to determine the appropriate damage die:
- 0-1 harm = d4
- 2-3 harm = d6
- 4-5 harm = d8
- 6-7 harm = d10
- 8+ harm = d12
Weaknesses
Finding and exploiting a creature’s weakness Enhances applicable damage die. Certain creatures may still require their weaknesses to be found to permanently destroy them or keep them from coming back.
Tags
Use the Appendix Item Tags as a means of porting over the tags from MotW. If there is not a close analogue, use the existing ones as guidance to make a ruling for the table.
Mothership 1e
Stress
Use as listed.
Hit Protection
Correlates to an enemy’s wounds
- 1 Wound = HP 1-5
- 2 Wound = HP 6-9
- 3 Wound = HP 10-13
- 4 Wound = HP 14+
Ability Scores
For Strength and Control, take Combat and Instinct, divide the values by 5 and add 3. There’s no direct analogue for Dexterity, so use Instinct as the baseline and adjust as needed. For quick conversion, use the table below.
| Mothership 1e | Liminal Horror |
|---|---|
| 0 | 3 |
| 5 | 4 |
| 10 | 5 |
| 15 | 6 |
| 20 | 7 |
| 25 | 8 |
| 30 | 9 |
| 35 | 10 |
| 40 | 11 |
| 45 | 12 |
| 50 | 13 |
| 55 | 14 |
| 60 | 15 |
| 65 | 16 |
| 70 | 17 |
| 75+ | 18+ |
Armor
Use the values below as a point of reference.
- Vaccsuit (3 AP) = Armor 1
- Hazard Suit (5 AP) = Armor 2
- Battle Dress (7-10 AP) = Armor 3
Combat
For quick conversion, use equivalent weapons on the Equipment Table (p.x) to determine damage. Otherwise, below is a rough conversion. Ignore damage modifiers when adapting.
- Minor (unarmed) 1d5 = d4
- Moderate (hand welder, revolver) 1d10 = d6
- Severe (SMG, flamethrower) 2d10 = d8
- Deadly (grenade, smart rifle) 3d10+ = d10 - d12
Triangle Agency
Monstrous Incursion
Use the Anomaly as the source of the weird in the adventure, driving the ramping tension due to its influence. Use the Focus, Impulse, Domain, History, and Appearance as the framework for the investigation.
Doom Clock
Use the Chaos effects to drive the Doom Clock and how the Incursion/Anomaly impacts the world around it.
Monsters
Use the Minor Anomaly as a means of creating Monsters that get in the way of the Investigators. The source of an Anomaly could easily be turned into a Resonant Artifact (p.x) to later be contained and potentially utilized by the Investigators.
Combat
Use Harm to determine a creature’s damage die:
- 1 harm = d4
- 2 harm = d6
- 3 harm = d8
- 4 harm = d10
- 5 harm = d12