Hold the Flood — Power and Attraction: the shared rule contract

r2 · 2026-09-06 · Lead Game and Systems Designer, adopting PM's r1 seed (782139) and keeping the editor's Glossary link (8afc3c) · In review · This page now states the rules every district must obey; the Design Document r14 (ec1b6c) sections 1, 3, 4 and 5 are the derivation and the worked examples it was validated against. Design Index · Expansion Brief · Design Document · Campaign (DES104) · World and Mystery · Glossary

What this page is. The Expansion Brief asks the lead to specify the shared rule contract before districts introduce exceptions, and the independent critic's REV104 criteria ask for it first, as one statement. This is that statement. Everything here is a proposal, carried over from the Design Document where it has survived nine review rounds; nothing is owner-approved, nothing has been played. A district may add to this contract. A district may not change what power, signal or charge mean. Where a district needs an exception, the exception must name the readable signal that announces it and the choice it improves, in that district's own "shared-rule diff" (section 7). The World and Mystery page remains the source for the mystery chain and the district fiction; this page is the source for the rules.

Adoption note. PM's r1 seed summarised Design Document r13. This revision validates it against r14, keeps its wording where it was exact, and corrects or completes it where it was not (section 9). The World and Mystery page's own statement of what stays fixed and what a district may add (WLD103, r20) agrees with this page clause for clause; where the two are worded differently, the rule is the same and this page is the one to cite for rules, theirs for the mystery. Under the Design Index's transfer protocol this is the author-approved integration edit for these rules; the editor may now replace the document's duplicates of the rule text with a link, keeping the document's examples, ledgers and derivations where they are. Until that link exists, the document's section 4 and this page say the same thing, and this page is the one to cite.

1. Conduction: water connects

Current present anywhere in a body of connected water is present everywhere in it. Two channels are one body when a valve, lock or breach joins them and both hold water. A dry bed does not conduct; a drained connection is no connection.
Ways to change the topology, all readable on the ground: a valve (joins or parts two channels), a drain or field pump (empties a channel), a lock (moves water between basins, section 7 of the Campaign page), and, in the rack, a chain of wet salvage bundles.
In the rack, equipment housings do not conduct; wet salvage bundles do, and a bundle touching a battery leaks that battery's charge through every bundle in the chain, shown as one drip per bundle. Insulation is the only slot that breaks a chain. Insulation worn by the surveyor lets them stand in energised water.
These are game rules and are not a claim about real electrical safety; the Reference page on electricity in water records the physics caveats.

Readable signal. Wet is wet on screen; energised water shows arcs along its edges; a joined channel's lamp, where one exists, is an indicator (section 4).

2. Power: a device works while its channel carries current

A device works only while the water or line it stands on carries current, and stops when the current stops. Devices: dispatch beacons, hatches and doors, gates, pumps and indicator lamps. The relay is the one stated exception: it is a source of signal, not a consumer of power; its drum is turned by a wheel in flowing water, the race above the weir, which carries no charge, so the valves can never light the yard from the relay's side, and drain R stops the drum without touching the district's power (World and Mystery r18, closing REV103-9). The exception is readable: the wheel turns in water that shows no arcs.
What supplies a district's own circuit is not stated on any page (REV104-4). Two candidates are on the world page as the campaign's final answers: the city runs on charge harvested from the Flood, or the head-works' flowing water drives it; the owner chooses through the Campaign page's decisions. Until then no district may depend on the answer, and every district's circuit is simply the district's own, switched at its panel.
Sources of current: a district's own circuit, switched from its panel, whose positions choose which branch is powered and are exclusive (one branch at a time, or off); and a coil discharge, which energises the water the surveyor is touching for the seconds the charge lasts.
The panel's thick cable is the power line. Switching it is instant and priced by what it darkens as well as by what it lights.

Readable signal. Steady light means powered; dark means unpowered; the thick cable is visibly thick.

3. Attraction: the signal chooses the intake; light draws the crowd

Intake. Each surge enters at one intake, chosen by the district's signal line: the panel's position sets the relay's lever, and at the dispatch the chosen intake's beacon flashes. Only the panel selects intake. Powering a beacon by any other means, including a coil, lights it but never makes it flash and never selects the next intake. The signal cable is thin; the dispatch pulse runs along it visibly. What a local dispatch requires, its drum's contact, the trunk's time from upstream, or both, is being settled on the world page under REV104-1, and this contract will carry the sentence the world designer adopts; the lead's reading is the critic's, that the drum makes the moment and the trunk permits it, so stopping either stops announced surges.
After entry. A crowd continuously moves toward the nearest lit beacon it can reach. If none is reachable, it spreads along the branch it entered by. Precedence, retarget or spread: a crowd whose beacon goes dark retargets to the nearest reachable lit beacon if there is one, and spreads only if there is none; a crowd holding at a lit beacon does not leave it for a farther one.
What is a beacon. The district's dispatch beacons and the portable beacon. Every other lamp is an indicator: it shows state and draws nothing.
Pursuit. Organisms within pursuit range chase the surveyor; pursuit is local and short, and a crowd's outward pressure (the press) is separate from it. At a doorway, organisms in pursuit come in one at a time.
Arrival. A surge is forty to a hundred and forty organisms entering over about half a minute, on the schedule the forecast shows.

Readable signal. Flashing means a dispatch; the thin cable is visibly thin; a crowd's target is the light it walks toward.

4. Charge: once per organism, ten per battery

Organisms carry charge and shed it once per expedition, visibly dimmer afterward. A kill drops a small mote of one unit. A stun in water sheds one large mote of five units per ten organisms stunned. Motes fade in seconds.
A battery holds ten units. A collected mote goes to the battery with the most room, linked or not, and to the battery placed earlier when rooms are equal; a full battery takes nothing; a battery the arc is drawing takes nothing until the burst ends. Charge left in a battery at extraction is lost at the dock, and charge never leaves a district with the player; what a district's own machines meter or move is that district's design (REV104-2, resolved as the world page asked).
A coil discharge needs a full linked battery and spends it; it stuns everything in the water the surveyor is touching for eight seconds. The arc drains a full linked battery over about ten seconds, one burst per battery, and returns no motes from organisms that have already shed.
Charge ledgers, per beat, are the check on every written expedition: dropped, collected, stored, expired, spent. Two empty batteries fill together under the collection rule, so a two-battery rack needs about nineteen kill motes before its first discharge; that is a cost of the rule, not a defect, and any district that gives the surveyor two batteries early must show where the charge comes from.

5. The rack

Two rows of three slots at the campaign's start. A slot holds one module or one bundle; the coil takes two. Each battery links to one module and each module accepts one link. Arrangement and linking happen only at shelters (docks when dry, and marked platforms). Modules picked up in the field go into any empty slot as found.
Growth is a campaign proposal, not a rule here: the Campaign page argues for a third row, unlocked by a discovery, because new module classes need slots; until the owner decides, six slots is the contract.

6. The expedition frame

Fifteen minutes; three dispatches on a forecast schedule; docks are hard stops for the Flood; extraction banks cargo and loses charge. The colony holds one dock dry per district it has reached, and which one is a colony choice with consequences and no upkeep.
A district may change the schedule's shape (the Tidal Barrier adds a second clock) but not the frame: an expedition still ends, docks still stop the Flood, and nothing decays between expeditions.

7. What a district may add, and the shared-rule diff it must publish

A district page states, in one short table, what it adds (a new device, a new way to change topology, a new enemy role, a new module), what it changes (ideally nothing), the signal that announces each addition, and the choice each addition improves. The test the critic will apply: a written expedition in that district whose choices could not occur in the pumping district. Additions that pass on paper so far, each proposed on the Campaign page: locks and basin levels; a powered rail and a moving beacon; a dispatch network with more than one panel; a second clock, the tide; and four enemy roles, each with a precedence question a single role cannot pose. Additions that fail: anything that makes a lamp draw, a coil select intake, an organism shed twice, or a device work without current.

8. Readable state, and two thresholds recorded by the Reference Researcher

The convention: steady means powered, flashing means a dispatch, dark means unpowered; wet and dry read by tint; enemy variants by size and tint. REF106 checked this convention against two published standards and found no defect, since nothing is built, and two things to hold in mind. Both are proposals here, for whoever owns presentation when that role exists, and the lead until then:

Wet and dry should not read by colour alone. A second channel is cheap in prose and expensive after art exists: proposed, a visible surface motion on wet ground (ripple or reflection) so that wet reads by movement as well as tint. Energised water already reads by its arcs, which is a non-colour channel.
Flash rates and arc area. The dispatch flash should be a slow pulse, about one to two per second, which is what a cue read at a glance wants anyway. Arcs on energised water should be local sparks along edges and contacts, never a whole-screen flash, which also keeps the signature act legible.

9. Validation of PM's seed, and what changed

Kept as exact: the two networks; the panel's positions; that injecting power selects nothing; continuous targeting of the nearest reachable lit beacon; spread with none reachable; that a held crowd does not leave for a farther beacon; that ordinary lamps are not beacons; the cables and the dispatch pulse as the learnable distinction; water, valves, pumps and insulation. Completed: the precedence stated as retarget or spread; the exact set of beacons; pursuit and the press; the arrival size and duration; the charge clauses and the collection rule; the rack rules; the expedition frame; readable state. Corrected: the seed cited r13; r14 (ec1b6c) is the revision validated against, and it changed the expedition-six numbers, not the rules. Closed since the seed: REV103-9, ruled on the world page at r18 (the relay runs on flowing water, a source and not a consumer), which clause 2 now carries as the one stated exception. Open from REV104 r1: what a local dispatch requires (REV104-1, the world page first, then clause 3) and what supplies the district's circuit (REV104-4, an owner decision listed on the Campaign page); REV104-2 is resolved in clause 4.

Bookkeeping

Sources read for r2. Expansion Brief PMU004 1a568e; Design Index 3cc078; this page's r1 seed 782139 and the editor's 8afc3c (Glossary link, kept); Tasks eb8c03 (DES104 Ready: start the shared-rule contract now); Design Document r14 ec1b6c; World and Mystery r18 d1d56a and r20 7699de (REV103-9 closed; WLD103's fixed contract and may-add list, which this page agrees with); Design Review REV103 r5 205bfb (REV104 criteria: the contract first) and REV104 r1 80a882 (REV104-1 to -5 on the world page, of which -2 and -4 fall to this contract); Reference/Readable State REF106 r1 e86ada.

PM report. Task: the Lead's validation and adoption of the Power and Attraction page, as the Expansion Brief, the Design Index and Tasks assign; artifact: this page r2 (r1 782139 and 8afc3c in history). No canonical decision changed; every rule is the Design Document's, restated, with the world page's r18 relay ruling carried; two presentation proposals added from REF106, labelled; REV104-2 resolved as asked; REV104-4 recorded as open. Evidence: written design against the cited revisions; no player data; nothing built, prototyped or tested. Risks: two sources for one rule set until the editor links the document here (EDT102); REV104-1 pending on the world page. Next handoff: the editor to record the transfer and replace the document's rule duplicates with a link; the critic to check this contract against the document at r14 and the world page at r20; the world designer to adopt the REV104-1 sentence, which this page then mirrors.