Already running B/X, Shadowdark, Old School Essentials, Basic Fantasy, or something else in that orbit?
Port The Chaos for:
- faster, single‑roll resolution - no separate attack/damage rolls, no save‑or‑die tables
- more flavourful morale via grit - keeps the OSR feel but adds personality
- improv‑ready creature & spell creation - generate monsters & magic in seconds
- unified d6 economy - simpler rolls, tighter outcomes, easier adjudication
-
table‑ready tools that reduce GM overhead - everything runs straight from the page or card deck
This page shows how its procedures (quick resolution, flavourful grit, simple d6 damage, and fast creature generation) map cleanly onto old‑school assumptions. Treat it like a toolbox: grab the bits that make your game run smoother, leave anything that doesn’t fit your table.
Use whatever d6s you've got. That's the only dice this needs.
Jump to: Conversion Philosophy · Core Rules · Character Creation · Creature Creation · Worked Creature Examples · Conflict · Weapons, Armour, Spells · Picking and Choosing
conversion philosophy
Don't try to perform fake mathematical conversions between fundamentally different dice economies. Preserve the things that already work, and translate the things that don't into the nearest functional equivalent. Mostly though, take it easy and go with what works for whoever's playing!
- HP → use directly
- Weapon damage → convert dice to 1d6 ± modifier
- Morale → grit score
- AC → convert to –1/–2/–3/–4 damage
- Attack bonus → bucket into ±0 / +1 / +2
- Special abilities → preserve fiction, translate mechanics
- Multi-attacks → one roll covers all
- Movement → advantage/disadvantage on positioning
- Spell damage → convert to 1d6 ± modifier
core rules
dive deeper into the core rules
The Chaos runs on two resolution methods, and you pick whichever fits the moment.
roll the odds
For anything uncertain that doesn't hang on a specific ability, like an opposed check, a coin flip moment, a "does the door hold" situation, roll 1d6. A roll of 4 or higher favours the character(s). 3 or lower and luck isn't on their side. Apply a ± modifier if the moment calls for it.
Porting it in: this slots in anywhere your system currently reaches for "GM ruling" or a flat d20 or d100 percentage chance check with no clear stat attached. If your game already has a reaction roll or morale mechanic, this is the same shape, just recoloured for general use.
roll the traits
If a character's stated intention is in doubt, or it's a reaction under pressure, roll 3d6 against the relevant trait score. Roll under the score and the intention succeeds. Apply a ± modifier if it's harder or easier than usual.
Porting it in: some OSR games already use roll-under ability checks, although the exact die and procedure vary. If your system uses 1d20-under-stat, for example, you can keep your existing scale and simply borrow the idea of separating intentional trait checks from general odds rolls. The trick worth stealing is the instinct of The Chaos to ask first "should this even need a roll?". If the fictional intention makes sense and nothing's opposing it, just let it happen and focus on what flows organically from it.
character creation
dive deeper into character creation
The Chaos uses six traits, each rolled with 3d6: Brawn, Smarts, Instinct, Agility, Vigor, Presence. High scores nudge you toward one of six soul types (Brawler, Weaver, Empath, Rascal, Tough Nut, Charmer), but nothing forces the pairing. It's a suggestion, not a class lock. Before play, you can bump your highest score by 1 and drop another by 2 (minimum 9), or take one re-roll if your spread is rough.
Porting it in: if your system already has six-ish stats, this is mostly a re-flavour exercise, map Brawn to Strength, Instinct to Wisdom, and so on, and keep your own generation method. What's worth taking wholesale is the soul type as suggestion, not requirement approach: let players see what their highest trait implies about a class or archetype, but don't hard-lock it. It keeps the process fast without flattening character choice.
health, stress, and wounds
Max health is 2d6 ± modifiers (or a flat 12 ± modifiers for a gentler curve). At zero health, roll 1d6: 1-2 you die immediately, 3-4 you take a lastin' wound (permanent -1 max health, roll or agree what and where), 5-6 you're shaken and take an automatic -1 to all rolls until it's addressed. These stack. Two lastin' wounds and you're done.
Stress works similarly: certain rolls prompt a stress check (1d6, 4+ is fine, 3 or under adds a stress point), and hitting 6 points triggers a roll on the stress table for a temporary complication, from hyper-focused (a bonus, oddly) to melt down (a serious penalty).
Porting it in: if your system's death and dying rules feel too binary (stable at 0, dead at some negative threshold), this three-tier "die, get scarred, or get shaken" table is easy to graft on regardless of how you calculate HP. The stress table is the more distinctive piece, most OSR games don't track a fear/stress resource at all, so this is a good standalone subsystem to import if you want more of a horror or attrition edge without switching your whole combat math.
A reminder while porting this over: none of these tables should ever tell a player what their character feels. They describe a mechanical effect. How the character experiences it, and how they roleplay through it, stays entirely in the player's hands.
creature creation
dive deeper into creature creation
This is arguably the easiest piece to lift wholesale, because it's designed to work with almost any stat block shape.
Roll 2d6 (or pick) across a stack of tables to build a creature on the fly: what kind of thing it is, what it looks like, how big it is, then three difficulty tiers (easy / hard / oh boy!) that set max health, to-hit modifier, damage, and grit score all at once. A separate table covers attack methods, defences, secondary abilities, and motivation, so you can flesh out a monster in under a minute without pre-writing anything.
In The Chaos, creature numbers scale with difficulty too: 3d6 if they're easy, 2d6 if hard, 1d6 if they're meant to stand alone, always having in mind how difficult you wish the scenarios to be for the players. Multiple weak creatures can also be bundled into a single minion group that acts as one entity with a stacking bonus, useful for keeping big fights fast. This keeps encounter difficulty predictable without needing XP budgets or CR math.
Porting it in: the tables themselves (kind, appearance, size, attack method, motivation) are system-agnostic flavour generators, you can use them as-is regardless of what math your creatures run on. The easy/hard/oh boy! difficulty tiers are the part to adapt: swap out the specific numbers for whatever your system's monster math looks like (HD, AC, damage dice), but keep the three-tier shape, since it gives you a fast improv scaling tool without needing a full bestiary open at the table. Note that The Chaos deliberately skips rolling creature traits up front, only rolling 3d6 for a trait if a contested check actually comes up. That's worth stealing on its own: don't pre-build what you don't need yet.
HP converts directly. AC converts approximately. Attack bonus needs to be re-scaled.
Systems like B/X build their monster to-hit around a d20, where attack bonus climbs steadily with Hit Dice. A +8 modifier on a d6 doesn't create a meaningful advantage. Against a 4+ target, it turns the roll into an automatic success. The Chaos keeps its own to-hit spread deliberately narrow (±0 / +1 / +2 across its easy / hard / oh boy! tiers) because a six-sided die can't absorb big swings the way a twenty-sided one can.
So rather than converting the bonus number directly, bucket the creature into the appropriate offensive tier:
- Low attack bonus (roughly HD 1-3, or a young/weak creature) → ±0
- Mid attack bonus (roughly HD 4-6, a genuine threat) → +1
- High attack bonus (roughly HD 7+, or anything built to challenge a whole party) → +2, stretching to +3 for something truly monstrous
Don't convert the B/X attack bonus. Convert the creature's overall offensive tier.
Everything else about the attack (how many per round, what it does, any special effects) can stay exactly as written in the stat block or as closely as makes sense. You're only re-scaling the one number that doesn't survive the jump from a d20 to a d6.
- Multiple Attacks. If a creature has multiple attacks, treat them as a single intention: one roll covers the whole attack routine, and on success, apply all listed effects; on failure, the opposing side lands a single hit.
- Specific Damage Type. If a creature or effect deals a specific damage type (fire, acid, cold, etc.), keep the fictional type but convert the damage to this game's usual 1d6 ± modifier. Resistances and immunities stay exactly as written.
- Saving Throws. If a creature or effect calls for a saving throw (paralysis, petrification, charm, breath weapon, etc.), again keep the fictional effect but attach it to a mechanic like stress for fear/confusion, lastin’ wounds for physical harm or temporary impairment.
- Movement. Movement rates convert loosely: faster creatures might gain advantage on positioning or surprise checks; slower creatures might suffer disadvantage. Exact distances aren’t needed in this game.
Handy shortcut: if your source system tracks a morale score on its own 2d6 scale, you can often use that number as the creature's grit score with little to no adjustment. Both mechanics are already built around the same 2d6 spread, so this is one of the few pieces that lines up almost exactly as-is.
worked examples: goblin | giant spider | wraith
Here's the full process run on two OSR stat blocks, a low-threat swarm monster and a high-threat undead with a signature special ability.
GOBLIN
core stats: AC 6, HD 1-1 (3 max hp), Att 1 × weapon (1d6), NA 2d8, THAC0 19, ML 7 (9 with king).
max health: 7, straight from the HP.
armour: AC 6 sits at the light end of the B/X armour scale, so convert it to -1 damage.
to hit: HD 1-1 is squarely in the low bucket, so ±0.
damage: 1d6, kept exactly as written.
grit score: ML 7 maps straight across (9 if a goblin king is leading the pack), since B/X morale already rolls on 2d6.
The Chaos stat line:
goblin
pallid, earth-skinned raiders with glowing red eyes, hate the sun, hunt in packs.
no. of them 2d6 | max health 7 | armour -1 (light)
to hit ±0 | damage 1d6 (weapon) | grit score 7 (9 with king)
can also struggle with sunlight, so ±1 penalty to rolls in sunlight.
needs loot, territory, or to prove themselves to whichever goblin king is watching.
GIANT SPIDER
core stats: AC 7, HD 2 (16 max hp), Att 1 × bite (1d8 + poison), NA 1d4, THAC0 18, ML 8, Neutral. Poison forces a save vs. poison or the victim dies. Climbs walls and ceilings; often surprises prey.
max health: 16, straight from the HP.
armour: AC 7 is barely armour at all. Convert to –0 damage. The spider’s real defence is mobility and ambush, not toughness.
to hit: HD 2 sits in the low attack bucket, so ±0. If you want this particular spider to feel especially lethal, nudging it to +1 is reasonable.
damage: 1d8, so convert it to 1d6 + 1.
grit score: ML 8 maps straight across. Spiders don’t flee easily, but they’re not fearless like undead.
specific problem: save‑or‑die poison. The Chaos doesn’t use saving throws or instant death effects. The fix is to preserve the fictional intent (a bite has serious, lasting consequences) and reattach it to whatever The Chaos already tracks. The cleanest equivalent is probably inflicting a lastin' wound, automatically adding a stress point, or just relaying a temporary condition ±1 penalty to all rolls.
The Chaos stat line:
giant spider
a skittering, silent hunter with venom that ruins you long before it kills you.
no. of them 1d6 | max health 16 | armour –0 (none)
to hit ±0 (or +1 if you want a nastier variant) | damage 1d6 + 1 + lastin’ wound | grit score 8
can also climb walls and ceilings effortlessly; gains advantage on surprise checks.
needs prey, territory, or to protect its egg‑cluster.
WRAITH
core stats: AC 3, HD 4** (32 max hp), Att 1 × touch (1d6 + energy drain), NA 1d4, THAC0 16, ML 12, Chaotic. Only harmed by silver or magic weapons. A successful hit permanently drains a level from the victim.
max health: 32, straight from the HP.
armour: AC 3 converts to -3 damage. The wraith's more important defence is its separate weapon immunity, which should remain a special ability rather than being folded into armour.
to hit: HD 4 lands in the mid bucket, so +1. If it feels underwhelming for a named, dread-inducing undead, that's a fair read, nudge it to +2 and treat the bump as a deliberate choice to make this particular wraith memorable, rather than a blanket rule for every HD 4 creature.
damage: 1d6, kept as written.
grit score: ML 12 maps straight across, and since 12 is the maximum possible 2d6 result, this creature will essentially never break and flee. Wraiths don't rout!
specific problem: energy drain. The Chaos doesn't use character levels, so "drains a level" has nothing to attach to. The fix with special abilities like this is to keep the fictional intent (a hit costs you something permanent and can't just be shrugged off) and reattach it to whatever The Chaos already tracks permanently. The cleanest equivalent is probably inflicting a lastin' wound or just a temporary condition ±1 penalty to all rolls.
also worth flagging: "only harmed by silver or magic weapons" isn't a damage modifier, and really, it's more of a hard immunity, and this game's armour system doesn't have a slot for that on its own. Note it as a standalone trait on the stat line rather than trying to fold it into the armour number.
The Chaos stat line:
wraith
a silent, drifting shape of pure malice, its touch cold enough to steal something you can't get back.
no. of them 1d6 | max health 32 | armour -3 (heavy)
to hit +1 (or +2, GM's call) | damage 1d6 + lastin' wound | grit score 12
can also only be harmed by silver or magic weapons, silvered dealing half damage.
needs to settle whatever grudge bound it to this place.
conflict
Conflict runs in 10-second rounds. Before it breaks out, you can roll 2d6 for distance, 1d6 for surprise, and 2d6 for grit, all at once if you like (roll 5d6 and split the dice across the three checks).
Each round in a fight:
- State intentions. Every player says what their character's doing this round.
- Grit check. Roll for how creatures/NPCs are reacting.
- Initiative. GM and one player roll 1d6 each. Higher goes first. Tied rolls mean both sides act simultaneously.
- Turns. The winning side rolls 1d6 ± modifiers per combatant. 4+ succeeds. Simple movement doesn't need a roll at all.
- Repeat until it's resolved, checking for stress, conditions, and damage along the way.
On a failed turn, the character or creature doesn't just whiff, the opposing side gets to capitalise, landing their own hit. There's no separate "attack roll" and "damage roll" for the acting side; one roll carries both success and consequence.
Porting it in: if your system uses a standard side-based initiative (roll once per side, not per combatant), this is close to how The Chaos already runs, so the swap is mostly conceptual: adopt the "loser takes a hit" resolution instead of a whiff, and consider folding your morale check into the grit roll at the top of each round instead of only checking morale after casualties. If your system uses individual initiative instead, you can still lift the "state intentions first, then resolve" structure, it forces commitment before the dice land, which speeds up the table and cuts down on second-guessing.
the grit check
Instead of (or alongside) a morale mechanic, roll 2d6 against a creature or NPC's grit score, or check a grit table for flavour. If the roll beats their grit score, they want no more of this and look for the exit.
Three grit tables exist for different intensities: typic (calm situations), spikin' (things heating up), and bonkers (all hell's broken loose), each giving personality to a 2d6 result, from violent down to chummy at the low end.
Porting it in: this is one of the easiest single pieces to lift wholesale. If your system has monster morale, replace the flat morale score with a grit score and use these tables (or write your own three-tier set) for flavour instead of a bare pass/fail. It reads far better at the table than "the goblins fail their morale check."
weapons, armour, spells
dive deeper into weapons, armour & spells
Once your Hit Dice, AC, and stat blocks are sitting alongside the game's health and grit scores, you don't need to rebuild your weapon list, armour list, or spellbook from scratch. Most of what you already own simply ports across.
weapons
OSR systems use different dice for different weapons (1d4 dagger, 1d6 sword, 1d8 spear, 1d10 two‑hander, etc.). The Chaos uses a unified damage die, always 1d6, with a small modifier based on weapon lethality.
If you're grabbing a weapon from another system, convert its damage die like this:
- 1d4 → 1d6–1
- 1d6 → 1d6
- 1d8 → 1d6+1
- 1d10 → 1d6+2
- 1d12 → 1d6+3
As usual, this isn't definitive, so go with what you all prefer. The idea is to keep weapon damage inside this game’s tighter range while preserving the relative lethality of each weapon. Everything else about the weapon (reach, handedness, special traits) can stay as written, and remember to use damage modifiers beyond these to reflect the condition of the weapon or armour it's striking.
Simple guide: use the list here to convert weapon damage dice to modifiers.
armour
The Chaos treats armour as a flat reduction to incoming damage, not a shift in the odds of getting hit. So instead of adding your system's AC to a to-hit target number, convert it into a flat damage modifier applied after a successful hit lands.
A rough conversion that keeps the maths simple:
- Light armour (leather, low AC bonus) → -1 damage
- Medium armour (chain, mid AC bonus) → -2 damage
- Heavy armour (plate, high AC bonus) → -3 or -4 damage
- Shields, if tracked separately → an extra -1
Don't chase exact AC-to-modifier precision here. These are gameplay conversions, not mathematical conversions. So just eyeball where your system's armour sits on a light-to-heavy scale and pick the matching number. It'll feel right at the table faster than any formula will get you there.
spells
If you just want the spells themselves, keep their existing casting rules unchanged, but if you'd prefer to import this game's approach to spellcasting, replace your existing casting roll or spell-slot procedure with an odds roll or roll-under traits check (3d6 under Smarts, or whichever trait you've mapped your caster's key stat to). Success means the spell works as written. Failure means it doesn't go off, and if you want a bit of The Chaos flavour, consider bolting on a simple consequence table for failed or pushed casts (a mini version of wild magicks), even just up to six rough-and-ready mishaps is enough to capture the feel without designing a whole new subsystem.
If a spell deals damage using a d20 or other dice The Chaos doesn't use, convert it into the game's usual damage language rather than introducing new dice. As a rough guide:
- 1d4 becomes 1d6-1
- 1d6 stays 1d6
- 1d8 becomes 1d6+1
- 1d10 becomes 1d6+2
- 1d12 becomes 1d6+3
- 1d20 becomes 1d6+7.
As usual, these aren't mathematical conversions; they're quick gameplay equivalents that keep spell damage within The Chaos tighter range.
Simple guide: same spells, same effects, new resolution roll. That's it.
picking and choosing
None of this needs adopting wholesale. Some ports that tend to work well on their own:
- Just the grit tables, dropped in as flavour on top of your existing morale mechanic
- Just the creature broiler tables, for fast improv monsters regardless of your combat math
- Just the roll-odds/roll-traits split, if your system currently has one flat resolution method and you want a lighter option for low-stakes calls
- Just the stress table, layered on top of your existing sanity, fear, or exhaustion mechanic if you've got one, or as a new one if you don't
Whatever you take from this page, the aim is the same: keep the rules light enough that they leave you room to focus on presenting conflict, fleshing out scenarios, and following what makes fictional sense in the moment. The Chaos is built to sit alongside old‑school play, so treat these procedures as tools you can reach for whenever they make your game run smoother.
If you need more help on this, catch me on socials @vengersdecks, or be sure to get in touch.