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A GM screen taken from the rules that actually run

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The figures a GM reaches for mid-scene, on one page: the order of
operations, the circumstance ladder, how a roll bands, reaction, the
combat round, hit locations, wounds and bleeding, both tracks, the way
home, the stations, and the environment.

Every number was checked by running the function rather than by reading
it — 58 of 58 against rules.mjs, including the eight that moved out of
ringbrp.mjs. That matters more than usual here, because `design/` still
carries four rulings the code has overtaken: hit points as CON+MAS, a
Major Wound at max(9, HP/3), "no hit locations, final", and marksmanship
style fixed by home-world gravity. rules.mjs is the authority and the
page says so at the top.

It is also written to drop straight onto a Loom board: 34 cards, 23
links, nothing swallowed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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co-authored by Claude Opus 5
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# THE CUSTODIANS — GM screen
> Every number on this page was checked against `rules.mjs` on 9 September 2026
> — 58 of 58 figures, by running the functions — not read out of the design
> specs. Where this and `design/`
> disagree, **the code is right and this page is stale** — `rules.mjs` is the
> single authority, imported by both the runtime and the pack builder so that
> packs cannot be built under one rule and played under another.
## How to read this
This is the sheet to have open while running, not the rules text. It carries the
figures you reach for mid-scene and nothing you can look up afterwards.
### Where these numbers live
| what | file |
| --- | --- |
| every pure rule formula, and rolling, banding and grading | `rules.mjs` |
| the six specs in `design/` | review history addressed to Codex — **not** current rules |
## Rolling
### The order of operations
Difficulty multiplies the rating **first**, then situational modifiers add.
| difficulty | rating becomes |
| --- | --- |
| Easy | × 2 |
| Average | unchanged |
| Difficult | ÷ 2, rounded down |
Then add circumstance and any other modifier. The result is clamped to 1–100, so
nothing is ever truly impossible or certain. A skill with a printed base of 5 or
more never drops below 5.
### The circumstance ladder
Applied after difficulty. **Capped at ±40 in total**, however many apply.
| | |
| --- | --- |
| Overwhelming | +30 |
| Favourable | +20 |
| Slightly good | +10 |
| Neutral | 0 |
| Slightly bad | −10 |
| Unfavourable | −20 |
| Severe | −30 |
### Reading the roll
From the effective chance, call it **B**:
| band | is |
| --- | --- |
| Critical | `ceil(B / 20)` or less |
| Special | `ceil(B / 5)` or less |
| Success | B or less |
| Fumble | `101 − ceil((101 − B) / 20)` or more |
Fumble is tested **first**. **96–99 never succeed**, whatever the chance. 00
always fumbles.
Against armour: a **critical ignores armour entirely**; a **special counts it as
half**, rounded down.
## Reaction — who goes first
Reaction runs on two axes and takes the better of them:
- **Reflex** = `ceil(DEX / 3)`
- **Awareness** = `ceil(Readiness / 10)`
Base = `3 × max(Reflex, Awareness)`, then a d6 and a modifier capped at ±3.
Marksmanship style is the agent's own choice — home worlds are gone, and nothing
determines it for them.
## The combat round
### Defending
Every defence after the first in a round is cumulative **−30%**. Two defences is
−60%, three is −90%. Standing in front of three people is possible and stupid.
### Fire modes
| mode | to hit | gives you |
| --- | --- | --- |
| Slow | +10 | reloads |
| Single | 0 | — |
| Fast | 0 | a second shot |
| Rapid | 0 | bursts |
| Beam | +5 | sustain |
A weapon with no mode set behaves as Single.
### The second shot
**−20% to both shots**, not just the second. The cost of hurrying is that you
hurried the first one too — which is what stops this being a free extra attack
for anyone holding a revolver.
### Bursts
| burst | rounds | to hit |
| --- | --- | --- |
| Short | 3 | −10 |
| Long | 6 | −20 |
| Full | 10 | −30 |
Hits are **capped, not proportional**:
| | success | special | critical |
| --- | --- | --- | --- |
| Short | 1 | 2 | 3 |
| Long | 2 | 4 | 5 |
| Full | 3 | 5 | 7 |
However many rounds connect, **a burst is one wound event** — one Major Wound
check, not one per round. Every round in the burst leaves the weapon regardless
of what hits. A failure or fumble connects with nothing.
### Range
| band | to hit |
| --- | --- |
| Short | 0 |
| Medium | −10 |
| Long | −30 |
| Extreme (to twice long) | −50 |
| Beyond | cannot be attempted |
### Two weapons
−20% main hand and −40% off hand; if trained, −20% to both.
## Damage and wounds
### Hit points
`HP = ceil((CON + SIZ) / 2)` — standard BRP.
**Major Wound = `ceil(HP / 2)`**: a single blow of half your hit points or more.
### The damage modifier
From STR + SIZ:
| STR + SIZ | modifier |
| --- | --- |
| up to 8 | −1d6 |
| 9–16 | −1d3 |
| 17–24 | 0 |
| 25–32 | +1d3 |
| 33–40 | +1d6 |
| 41–50 | +2d6 |
| 51–60 | +3d6 |
| 61–70 | +4d6 |
| 71+ | +`4 + ceil((total − 70) / 10)`d6 |
### Hit locations (1D20)
| melee | ranged | location | share of HP |
| --- | --- | --- | --- |
| 1–4 | 1–3 | Right leg | 42% |
| 5–8 | 4–6 | Left leg | 42% |
| 9–11 | 7–10 | Abdomen | 42% |
| 12 | 11–15 | **Chest** | 50% |
| 13–15 | 16–17 | Right arm | 35% |
| 16–18 | 18–19 | Left arm | 35% |
| 19–20 | 20 | **Head** | 40% |
Ranged fire favours the chest, melee the legs — the two columns are different
distributions, not one table read twice.
A location's own pool is that share of total HP, rounded up. At its maximum the
location is **disabled**; at twice its maximum, **destroyed**. Location damage
folds together with Major Wound effects additively: both are true about the same
body at once.
### The Major Wound table (1D10)
| d10 | wound | what it does |
| --- | --- | --- |
| 1 | Concussed | −20% to everything |
| 2 | Winded | −20% physical, and you lose your action |
| 3 | Bleeding | 1 HP at the end of each round |
| 4 | Manipulation | −30% manipulation |
| 5 | Mobility | −30% physical, MOV halved |
| 6 | Deep bleeding | 2 HP at the end of each round |
| 7 | Sensory | −40% perception, and −40% manipulation (sight) or communication (hearing) |
| 8 | Broken | −30% manipulation, or −30% physical and MOV halved |
| 9 | Crippling | defence only, MOV 1 |
| 10 | Catastrophic | unconscious, defence only, MOV 1 |
Wounds **stack**: two concussions is −40%, and a Major Wound stacks with a
shattered limb, because both are true about the same body. Where a wound splits
two ways and the variant was never recorded, the harsher reading applies.
### Bleeding
| | per round | stopped by |
| --- | --- | --- |
| Bleeding | 1 | a successful First Aid, or Medicine at any difficulty |
| Deep bleeding | 2 | a **Difficult** First Aid, or Medicine at any difficulty |
Any one listed stop is enough. First Aid restoring hit points does not clear the
wound — the bleed keeps running until something on that list lands.
## Panic — the short track
0 to 5, **upward**, minutes long: what is happening to you *now*.
| | track | penalty |
| --- | --- | --- |
| Steady | 0 | — |
| Rattled | 1 | — |
| Shaken | 2 | −5% |
| Losing it | 3 | −10% |
| Overwhelmed | 4 | −20% |
| Broken | 5 | −20%, and they break |
Talking someone down: a success takes one point off, a special or critical takes
two — and **a fumble puts one on**.
## Coherence — the long track
0 to 10, **downward**, campaign length: what knowing has cost you. Do not confuse
the two tracks at the table.
| band | from | all rolls | communication |
| --- | --- | --- | --- |
| Anchored | 8 | — | — |
| Loose | 5 | — | −5% |
| Adrift | 3 | −5% | −10% |
| Unmoored | 1 | −10% | −20%, and −30% to the return |
| Displaced | 0 | −20% | −30% — permanent |
### What it costs
| | |
| --- | --- |
| Fumbling a crossing | 1 |
| Witnessing a paradox | 1 |
| Using crossing tech | 1 |
| Breaking local law | 1 |
| Overstaying | 1 |
| Meeting yourself | 2 |
| Killing a duplicate | 3 |
### Getting it back
One point each: a debrief, a week of downtime, an anchor object.
## The way home
### The return clock
Three steps. It is the *crossing* that gets harder, not the people — a cost the
players can see coming.
| steps | the return is at |
| --- | --- |
| 0 | — |
| 1 | −10% |
| 2 | −20%, **and Difficult** |
| 3 | −30%, and Difficult |
### Extraction
| roll | completes? | clock |
| --- | --- | --- |
| Critical | yes | a step **back** |
| Special | yes | — |
| Success | yes | — |
| Failure | yes | +1 |
| Fumble | **no** | +1 |
Nothing else takes damage from a bad extraction. Getting out badly does not hurt
anyone on the causeway; it makes the next crossing harder.
## Craft actions — the stations
Every agent takes a station, each uses a skill somebody already has, and the
round is one roll each in the normal reaction order. No vector arithmetic, no
map — range is a band.
| station | skill | does | heat |
| --- | --- | --- | --- |
| Helm | Pilot | changes the band | +1 |
| Guns | Energy Weapon | damage | +2, and on a failure too |
| Sensors | Computer Use | marks a target | — |
| Engines | Engineering | sheds heat | −3 |
| Damage control | Repair | hull | — |
| Signals | Persuade | talking | — |
| Medical | First Aid | the crew | — |
| Anchor | Transposition | escape | +2 |
### Heat
Runs 0–10. **Loud from 4. Blind from 6. Slow from 8.**
### Space range bands
| band | to hit |
| --- | --- |
| Docked | 0 |
| Knife | +20 |
| Close | +10 |
| Standoff | −10 |
| Distant | −30 |
| Gone | cannot be attempted |
## The environment
### Falling
1d6 per 3 metres, to a maximum of 20 dice — reached at 60 metres, and nothing
above that falls harder. **Fall damage ignores armour.**
### Drowning and airlessness
1 point per round. Caught unprepared, you hold your breath half as long.