4. **Break.** The release is resolved: everything it sent into the room is cleared, or you complete a seal that closes its source. Killing faster than bodies arrive keeps a lane clear, but it does not stop a source that is still feeding. You can also get out past a bulkhead or outrun the woken area — that saves you, though it resolves nothing. Closing a source stops its incoming flow but leaves creatures already inside active. Once the current space is cleared or safely separated from them, the music and room silhouette release, and the lull belongs to looking, salvaging and deciding where to go.

Crowds come from **source areas**: wards, lift wells, ducts, flooded concourses, sealed volumes — places that physically hold bodies and connect to the route you are on. Bodies always arrive through routes you can see or hear, and no extra wave arrives because your build was efficient. A warned route can still carry enemies around or behind you.

**Population initialization happens once, before an expedition begins.** Where an authored route mapping names the source, allocation, standing positions and warnings, a finite group may already have walked from one named, still-open source aperture along the current open walking route and be standing farther down that route when the astronaut leaves the ship. Its bodies are deducted from that source's finite population; they are not copies, and loading, leaving and re-entering, waiting or fighting efficiently never initializes them again. Once play begins, a body not already placed on the route can arrive only by physically emerging from its shown aperture or crossing a visible neighbouring threshold after a warning. An initialized standing band is not a release that committed offscreen: its own approach warning and commitment occur when it wakes into the player's route.

**Scale.** In a broad ward, dock or gallery a developed crowd might show 80 to 150 bodies at once and pass several hundred through its full crest. A narrow corridor shows fewer at once but a continuous river through doors, lifts and ducts. A small room can host a short teaching moment — one new creature, one new warning — but the way to it still carries the crowd. Where a placed room is too small for the crowd its encounter needs, that is rework to do; [Encounter And Mechanism Placement Inventory](/Hold%20The%20Flood/Encounter%20And%20Mechanism%20Placement%20Inventory) lists those obligations.

Noise and machinery wake the next stage. Loud work, alarms and a Caller that finishes its call can each wake an adjacent source, and its route is always shown before the crowd arrives. Cutting the alarm, stopping the Caller or completing a physical closure before the release commits prevents it. After commitment, cutting the alarm cannot recall attackers already released; completing a physical seal can still stop their access. Bodies already beyond that closure remain active.

Letting it happen can be a choice, too. A player with a strong build may want the second surge. Deliberately waking a large machine brings a much larger surge and often reveals new space — [The Game](/Hold%20The%20Flood/The%20Game) shows one.

Clearing the current space, or safely separating it from remaining threats, earns a lull: time to investigate, salvage and choose a route. The room shows whether each source is sealed, exhausted for the present surge or still able to release another announced stage. Clearing all committed attackers or sealing their access before the peak resolves that committed stage immediately. Creatures already beyond a completed seal remain dangerous until cleared or safely separated. Or you can simply get out past a bulkhead or outrun the woken area.

An occupied area next door can still send bodies through a visible route, with sound and door movement to warn you. Permanent seals remain closed. The arrangement and timing of further pressure must leave useful quiet for discovery; the rules for replenishment during an ongoing expedition remain to be designed. Returning home prepares fresh crowds for the next expedition, while permanent work remains done.

**Ordinary fighting supplies regular temporary combat growth. Larger transformations come at major horde milestones.** Growth happens while the fight develops, so out-fighting an incoming crowd can strengthen the rig before its whole release is resolved. Major milestones mark bigger changes in what the build can do. [Build Rules](/Hold%20The%20Flood/Build%20Rules) owns the upgrade effects and connections.

[Two Trips, Two Different Builds](/Hold%20The%20Flood/Upgrade%20Choices) works through two paid Tune opportunities on the longer sealed-source route. Its four-offer sample also proposes what to show when only one or no new compatible effect remains, while preserving banked choices and the separately earned major. The small pool can eventually run out of new choices during an expedition.

A **major horde milestone** is a named physical event inside a major placement, not another three-mark threshold and not the reward for clearing the room. The representative Balance Gallery remembers two once-per-expedition facts in either order: **horde engaged**, when its first announced band commits either from an unsealed local feeding mouth or through the gallery's outer walking threshold from a named, currently connected source, and **Bellback answered**, when the first Bellback threat is countered or Bellback is defeated. A counter means its locked cone is escaped or put behind the fixed rib until the wave releases, a faced Barrier catches the wave, its unfinished brace is interrupted by displacement, or Bellback is defeated. Taking an unblocked hit does not set the answer, but a later valid counter or defeat can. A walking-threshold band counts only if the authored route identifies its source, conserves that source's finite population and warns the crossing in the gallery; adjacency alone creates no crowd.

As soon as both facts are true, the gallery announces **transformation ready** once. The no-special-equipment baseline is concrete: let the cone lock, step behind the rib, and let the wave strike structure; that records the answer. If a powerful rig defeats Bellback before the first gallery band commits, defeat records the answer and the later band commitment completes the milestone. If the band commits first, the next valid counter completes it. The first Bellback warning and first valid band commitment are staged during the early gather, before that band can reach its Break Mark, so answering their first opportunities leaves later bodies to fight. Bellback never becomes invulnerable, no replacement appears, and neither legitimate cover play nor efficient defeat loses the offer. The larger transformation remains separate from the Tune queue and can be taken in the paused journal while later bands and most of the crowd can still crest.

The [Receiver Vault Expedition](/Hold%20The%20Flood/Receiver%20Vault%20Expedition) develops another proposed milestone, **Turn the shelter**, through a committed hall band and a visible answer to Shutterback's protection. Its complete scene shows the ordinary flank, early defeat, source closures, a current Ricochet transformation and a quiet discovery. A proposed shorter walking arrangement can make this the first major offer; the longer Balance Gallery route keeps its earlier reward. The new route, band timing and useful remaining crowd are placement proposals, with their costs explained in that article.

- **Everything physical you carry comes home**, even after death. Oxygen breathed and material consumed stay spent. Ordinary condition is restored for the next trip.

- **Permanent changes remain.** Unlocked doors, selected room connections, completed permanent work and permanent source seals keep their states. The new population must use sources and routes consistent with those changes.

| **5:45–6:40** | Both unsealed mouths pour at once. Once one band commits and the Bellback threat has been answered in either order, the major transformation becomes ready immediately. Around **5:50–6:05** is the illustrative timing for this pass; an earlier successful answer grants it earlier, including while coupling is still running. The player chooses it in the journal and has later bands and the remaining crowd in which to enjoy it. An early seal previews the actual number of possible marks it prevents. |

At the current proposal of 1 O per 30 seconds, 12 O in the suit plus one 8 O canister is ten minutes of base breathing. By 4:25, base breathing has used about 8.8 O, leaving 3.2 O in the suit. The full 80 seconds of coupling moves 8 O while another 2.7 O is breathed, so 5:45 shows 8.5 O in the suit and an empty vessel. The remaining 2:35 consumes about 5.2 O; total base breathing by return is about 16.7 O. Arrival at 8:20 therefore shows about **3.3 O in the suit**, or 1:40 of base breathing. The full transfer, not its first 30 seconds, is included in the existing timeline.

This reversible paper pass covers one harder state of the same living-return arrangement: R11's quarantine grille, both R17 ward doors and both R25 feeding mouths are permanently shut; R17's internal passage is open. It does not reopen or relocate any of them. It proposes a **second ordinary walking threshold in R27**, on the wall away from its exchanger release, cooling fixture and Mara's clean abort apron; this is added geometry, not an already established exit. In this arrangement it meets R35 Receiver Vault Approach's existing entry threshold. It is separate from R27's R face, creates no network signal or room, and leaves R35's pillars, side-mouth controls, far hatch and R36 opening in their present relation. Live pressure through it must be cleared or separated before R27 can qualify as Mara's clean abort; the new threshold grants no shorter rescue.

| **What the player sees** | R17's ward previews and R25's crowded mouths announce pressure beside each fight. | Empty ward windows and locked mouths prove the permanent work. Two separated standing groups in R17, then scuffs, shipward-facing bodies and successive threshold movement, point outward through R20, R25 and R26→R27→R35. The ship side of the shut R11 grille stays empty. |

| **What completed work buys** | The R11 seal removes one source; the passage can skip the ward bands or shorten return. | All local side injections are gone, so pressure is one readable outward column. The passage bypasses both R17 bands at the cost of two marks, or shortens the earned-quiet return. It is two-way and does not prevent pursuit. |

The paid sequence is concrete without becoming a gate. With the existing Storm Choir example, the pre-gallery Tune can add **Echoing Arc**, so ordinary shots branch visibly through the first dense R25 band. Answering Bellback can then ready **Thunderhead**; its manual stored-charge burst breaks roughly forty well-packed ordinary bodies while the surviving first band and second rear band keep the transformed rig relevant. Another compatible rig receives its own offers, and the no-upgrade baseline can still cross with the rib and ordinary fire. The major is never delayed until a Tune is taken.

The renewed Bellback is explicitly one body in the R35-owned R25 allocation, counted within its first cohort rather than added to the total. The existing R20 Glass Siphon is likewise one of that room’s 20–30 source-owned bodies, placed across its pillars before departure; it is not another source or a replacement triggered by a kill. A Bellback defeated on the prior expedition stays defeated there; the next expedition initializes exactly this one before departure, and no other Bellback appears if it is defeated early. This is a proposed composition rule for this mapped source, not a global special-enemy exception. R35's 80–150 simultaneous occupancy is preserved rather than treated as its total, so its later fight is not weakened in head count. The cost is the newly proposed 220–370 total, longer-lived population state and added R27 threshold; their clarity, space and performance are unvalidated. R35's separate far-wall stage still requires its existing Caller and is not included in the total.

Clearing or separating each forward group preserves the R17 panel and R20 counter lulls; any surviving R20 Glass Siphon remains a creature threat, and the Breath Bank continues its mechanism cycle until the player deals with it. A cleared crowd does not switch off that machine. Clearing gallery pressure preserves the far-wall discovery lull. No timer, load or re-entry refills those spaces. The safe ship, R11 rescue leg and limited quiet first-latch lesson are unchanged.

A **living return** with the same arrangement initializes this allocation once again. After a **death**, the unjoined R27→R35 relation may move and becomes historical. Another named source may feed the route only after its own allocation, walking path and warnings are authored; otherwise this corridor stays quiet while the owner's fresh combat and growth direction is served at another current frontier. That conditional coverage is a limitation of this proposal, not a settled exception. **Strongest alternative:** keep the completed corridor quiet and place an equivalent ordinary climb and major opportunity at the first open frontier. It can preserve build development, but on a different itinerary; the accepted cost is losing fresh combat on the familiar route and reducing the R17 passage mostly to safe travel. The migration pass instead risks a harder-to-read distant source and a larger active population budget. Neither direction has established fun, balance, readability or performance.

- Damage, health, warning timings and displacement.

- How further pressure or replenishment works during an ongoing expedition, while preserving useful quiet.

- Major milestone events for placements other than the representative Balance Gallery and Cable Junction moving scan.

- Field healing and lasting injuries are not yet designed.