JARLS: Pressure Drop
Extended mechanics for Stress, Bonds, and Heat
I say, and when it drops, oh, you gonna feel it
Know what you were doing's wrong
I say, when it drop, oh, you gonna feel it
Know what you were doing's wrong
– Toots and the Maytals
The Core Rules give you fast resolution. Pressure gives you consequences that accumulate, relationships that fracture, and attention that never fades. Use these when you want sessions to have weight—when yesterday's choices haunt tomorrow's rolls.
In this supplement, we cover the following mechanics:
- Stress (psychological/temporal pressure)
- Bonds (crew cohesion/causal entanglement)
- Heat (external attention/timeline instability)
- How to combine them
- Adaptation notes for different genres
Compatibility: Works with any JARLS game. Referenced by JARLS: Heist and JARLS: Klein Bottle.
WHAT STRESS REPRESENTS
Pressure stretched too thin. The moment before breakthrough or breakdown.
In heist games: adrenaline, fear, guilt In time travel: temporal coherence, causal strain In horror: sanity, dread accumulation In war: combat shock, moral injury
CORE MECHANIC
Stress starts at 0. Mark +1 when:
- HP drops below half
- You witness trauma (death, violence, suffering)
- Your specialty fails publicly
- You push beyond limits (exhaustion, injury, impossible demands)
- [Genre-specific triggers—see adaptation notes]
When Stress ≥ Savvy, make a Stress Check before high-pressure tasks: 1d20 + Savvy vs. 12
SUCCESS: CLARITY (choose one)
- Hyper-Focus: +2 to next roll
- Sudden Insight: Ask GM one yes/no question about immediate situation
- Adrenaline Surge: Ignore wound penalties this scene
- Cold Professionalism: Reduce one ally's Stress by 1 (once per scene)
FAILURE: SLIP (choose one)
- Misstep: Small error (drop gear, advance Clock, minor consequence)
- Tell: Nerves show; next social interaction is Hard (+2 DM)
- Snap Decision: Solve problem immediately but lose 1 Bond with ally
- Doubt: Pressure spreads—one visible ally must also check Stress
- Need: Must spend next action coping (can't act productively)
- Confession Impulse: Almost blurt dangerous truth (next action spent clamping down)
BREAKING POINT (Stress 6+)
Roll 1d20 + Savvy vs. 14 (Hard)
Success: Path A - THE CRUCIBLE Pressure tempered you. At end of session, choose:
- Increase Savvy by +1 (max +3)
- Replace Flaw with new Edge
- Gain permanent scar but reset Stress to 0
Failure: Path B - THE BREAK You crack. At end of session, choose:
- Retire (character exits play, becomes NPC)
- Flip (betray crew, surrender, go solo)
- Snap (act out destructively, burn bridges)
REDUCING STRESS
Mid-session:
- The Breath: Skip action, center yourself. Reduce Stress by 1d2. (Not during combat)
Downtime:
- Medical Attention: +2d4 HP, –1d4 Stress (costs resources)
- Full Rest: Restore HP, reset Stress to 0 (costs time)
- Vice: –1d3 Stress but GM adds complication (addiction, debt, danger)
ADAPTATION NOTES
- Heist: Add trigger: "Innocent endangered by your actions" (+1)
- Time Travel: Add trigger: "Encounter another version of yourself" (+1), "Witness paradox" (+1)
- Horror: Stress called "Dread"; Breaking Point = insanity
- War: Add trigger: "Civilian casualties" (+1); Cold Professionalism very important
- Social Drama: Stress represents emotional exhaustion, not fear
WHAT BONDS REPRESENT
How much you trust each other. How far you'll go for them.
In heist games: crew loyalty In time travel: causal entanglement between versions of self In military: unit cohesion In horror: who you'll sacrifice to survive
CORE MECHANIC
Track Bonds between each pair of PCs.
- 3 PCs = 3 Bond relationships
- 4 PCs = 6 Bond relationships
Bonds start at 2 (neutral professionals)
GAINING BONDS (+1)
- Save someone's life (take bullet, go back for them, sacrifice safety)
- Give up resources to help (share take, give gear, forfeit advantage)
- Cover mistake without complaint
- Succeed at high-stakes cooperative action
LOSING BONDS (–1)
- Endanger them through recklessness (blow cover, trigger alarm, bring heat)
- Question competence publicly ("You can't handle this," "Let me do it instead")
- Break plan without warning (improvise wildly, abandon post)
- Take their share (steal, cut them out, negotiate behind back)
BOND EFFECTS
Bonds 0-1: HOSTILE
- Cannot Assist each other on rolls
- Cannot use cooperative mechanics
- Joint actions take –2 penalty
- One bad moment from turning on each other
Bonds 2: NEUTRAL PROFESSIONALS
- May Assist: Ally helps, you gain +2 to roll
- May Cover: Ally volunteers to take complication for you (their choice)
Bonds 3+: BONDED
- May Grant Advantage: Ally helps, roll 2d20 keep higher (can't stack with Assist)
- May Cover at Distance: Ally takes complication even if not in scene
- Once per session: Bonded ally can automatically steady you when you fail Stress check (costs their action, must be in scene)
SPENDING BONDS TACTICALLY
Some moves cost Bonds to use:
Cover Fire (costs 1 Bond)
- Declare covering ally's action
- They gain +2 but you're exposed (next attack on you at +2)
Come Back For Me (costs 1 Bond with specific PC)
- When captured/pinned, declare: "We agreed—you always come back"
- That PC must attempt rescue
- Success: both gain +2 Bonds. Failure: lose all Bonds with them.
ADAPTATION NOTES
- Heist: Use as written
- Time Travel: Bonds represent causal entanglement between PCs or between you and your other selves. High Bonds = more likely to create stable loops. Bonds 0 = diverging timelines.
- Horror: Bonds called "Trust"; Breaking Bonds at crucial moment = betrayal for survival
- Military: Bonds called "Unit Cohesion"; low Bonds = friendly fire risk
- Rivalry Games: Start Bonds at 1; some competitive moves intentionally reduce Bonds
WHAT HEAT REPRESENTS
External attention. Pursuit that never stops.
In heist games: law enforcement investigation In time travel: timeline instability, Agency attention In spy thriller: hostile intelligence services In horror: the thing hunting you
CORE MECHANIC
Heat starts at 0. Never decreases on its own.
INCREASING HEAT
- Witnesses see faces/crimes (+1)
- Alarms trigger (+1)
- You're identified (name, prints, signature) (+1)
- Property damage (+1)
- Someone dies (+2)
- [Genre-specific: federal interest, paradox created, etc.] (+2)
HEAT EFFECTS
Heat 0-2: SAFE
- Background concern only
- No mechanical penalty
Heat 3-4: ACTIVE RESPONSE
- All risky rolls are Hard (+2 DM)
- [Genre: cops looking, timeline flagged, hunters circling]
Heat 5-6: ESCALATION
- [Genre: SWAT/tactical units, Cleaners deployed, elite pursuers]
- Heat +2 DM stacks with difficulty:
- Standard task = 14 (Hard)
- Hard task = 16 (Extreme)
Heat 7+: MAXIMUM PRESSURE
- [Genre: Federal involvement, erasure protocol, no escape]
- Hunted across jurisdictions/timelines
- No statute of limitations
REDUCING HEAT (Downtime)
Lay Low (costs time)
- Roll 1d3, reduce Heat by that much
- Costs week+ of downtime, can't take other actions
Bribe/Manipulate (costs resources)
- Pay escalating cost per Heat point
- Only works below Heat 5 (top-tier attention can't be bought)
Leave Jurisdiction (costs connections)
- Move to different location/timeline
- Reduce Heat by 3
- Lose all local contacts, safehouses, resources
- Start over somewhere new
ADAPTATION NOTES
- Heist: Use as written (law enforcement)
- Time Travel: Rename "Instability"; represents timeline attention, not police. At Heat 5+ Cleaners (erasure agents) deploy.
- Spy Thriller: Heat = "Exposure"; hostile services tracking you
- Horror: Heat = "Attention"; the monster knows where you are
- Post-Apocalypse: Heat = "Reputation"; factions remember what you did
COMBINING WITH STRESS
When Heat is high (3+), every risky roll becomes Harder (+2 DM). This makes Stress checks trigger more often (more failures = more Stress). High Heat creates Stress spiral: harder rolls → more failures → more Stress → worse performance.
This is intentional. External pressure (Heat) creates internal pressure (Stress) creates relationship strain (Bonds).
THE PRESSURE TRIANGLE
Stress (internal): Am I breaking? Bonds (interpersonal): Are we fracturing? Heat (external): Are they closing in?
Each system feeds the others:
- High Heat makes rolls harder → more Stress
- High Stress causes Snap Decisions → Bonds drop
- Low Bonds means no one Covers you → more Stress
- Desperate actions to reduce Stress → more Heat
CALIBRATING FOR YOUR TABLE
Light Pressure (one system):
- Use just Stress for psychological drama
- Use just Bonds for relationship focus
- Use just Heat for chase/pursuit tension
Medium Pressure (two systems):
- Stress + Bonds = character-focused drama
- Stress + Heat = individual under siege
- Bonds + Heat = crew vs. the world
Full Pressure (all three):
- Maximum tragic weight
- Everything affects everything
- For experienced players who want consequences to compound
STARTING VALUES
Standard start:
- Stress: 0
- Bonds: 2 (between each pair)
- Heat: 0
Hard mode start:
- Stress: 1 (already rattled)
- Bonds: 1 (don't trust each other yet)
- Heat: 2 (already being watched)
Campaign continuation:
- Carry Stress/Heat from previous session
- Bonds evolve naturally through play
GENRE ADAPTATIONS
HEIST (Crime Drama)
Stress triggers:
- Innocent endangered by your actions
- Crew member captured
- Civilians witness violence
Bonds represent: Professional trust, personal loyalty
Heat represents: Law enforcement investigation
- Heat 3: Active manhunt, descriptions broadcast
- Heat 5: SWAT, helicopters, roadblocks
- Heat 7: FBI, interstate coordination
THE KLEIN BOTTLE (Time Travel Tragedy)
Stress triggers:
- Encounter another version of yourself
- Witness paradox or impossible event
- Bridge (displaced person) destabilizes
- Alter your own past
Stress renamed Coherence Loss Bonds renamed Entanglement (with other PCs and other selves) Heat renamed Instability
Heat represents: Timeline attention, Agency correction protocols
- Heat 3: Timeline flagged for monitoring
- Heat 5: Cleaners deployed (erasure agents)
- Heat 7: Severance protocol—retroactive removal
Special rule: Entanglement 10 = Critical Mass (see Klein Bottle zine)
HORROR (Survival)
Stress triggers:
- Witness death/gore
- Something impossible happens
- Supplies run low
- Someone you know transforms/dies
Stress renamed Dread Breaking Point = Insanity or Catatonia
Bonds: Who you'll sacrifice to survive Heat renamed Attention: The monster knows where you are
WAR (Military Drama)
Stress triggers:
- Civilian casualties
- Friendly fire incident
- Orders conflict with morals
- Prolonged combat
Bonds renamed Unit Cohesion Low Bonds = friendly fire risk, hesitation, abandonment
Heat represents: Enemy attention, escalating opposition
CYBERPUNK (Corporate Dystopia)
Stress triggers:
- Cyberware malfunction
- Corp netrunner counterhacks
- Witness state violence
Bonds: Who you trust when everyone's wired and recorded Heat renamed Exposure: Corps/police tracking your SIN/identity
QUICK REFERENCE
STRESS
- Starts 0, mark when: injured, trauma, specialty fails, push limits
- Check when Stress ≥ Savvy: 1d20+Savvy vs 12
- Success = Clarity (4 benefits)
- Failure = Slip (6 complications)
- Stress 6+ = Breaking Point (1d20+Savvy vs 14)
BONDS
- Start 2 between each PC pair
- Gain +1: save life, sacrifice, cover mistake
- Lose –1: endanger, question, break plan, steal
- 0-1 = Hostile (can't Assist)
- 2 = Neutral (can Assist +2)
- 3+ = Bonded (Advantage, Cover at distance, steady once/session)
HEAT
- Starts 0, never decreases naturally
- Increase: witnesses (+1), alarms (+1), ID'd (+1), damage (+1), death (+2), major (+2)
- 3-4: All risky rolls Hard (+2 DM)
- 5-6: Escalation, stacking penalties
- 7+: Maximum pursuit
EXAMPLE: THE SPIRAL
Session 3 of a heist campaign.
Current state:
- Murphy (Driver): Stress 2, Heat 3
- Banks (Hitter): Stress 3
- Murphy ↔ Banks: Bonds 2
The Job:
Murphy drives getaway. Makes Agility check to lose pursuit.
Rolls 1d20+3 (Agility) = 11 Needs 14 (Standard 12 + Heat penalty +2) Miss.
GM offers: Cost ("you lose them but the car's totaled—you're on foot") or Snag ("a cop gets your plates—+1 Heat").
Murphy takes the Snag. Heat rises to 4.
Banks, in backseat, says: "I told you to take the highway." This questions Murphy's competence publicly: –1 Bond. Murphy ↔ Banks now at Bonds 1.
Murphy's Stress rises to 3 (specialty failed publicly). Stress now = Savvy. Must check before next risky action.
Later: Murphy tries to hotwire new car. Stress Check first: 1d20+2 (Savvy) = 8. Needs 12. Fails.
Takes Snap Decision Slip: solves it immediately (hotwires car) but loses 1 Bond with Banks. Murphy ↔ Banks drops to Bonds 0 (Hostile).
Next job: Banks can't Assist Murphy. They're fractured.
Murphy's at Stress 3, Heat 4 (all rolls are +2 DM). Next failure might push Stress to 6—Breaking Point territory.
This is how the spiral works. One bad roll cascades.
CREDITS AND LICENSING
JARLS is a loose hack of Mörk Borg, CY_BORG, and Death In Space, with more than a nod to Twilight 2000’s Cool Under Fire mechanics.