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.

Each source releases its crowd in **stages**: a finite surge the room announces, from a source you can identify. A stage commits when its announced attackers and arrivals are released. While it is feeding, out-killing it keeps a lane open but does not stop it. Once committed, it ends when you clear all its committed attackers or complete a physical seal that ends their access. Walking away ends your part in it, not the stage. A further stage exists only where the room announces and sources one — a machine waking, a new mouth opening. Finite sources are fine; what the design avoids is an encounter that is over after five enemies. Sources feed through apertures — grilles, hatches, ward doors, ducts — that are separate from the passages you walk through, so sealing one never closes a route you need.

**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.

The exact growth meter, pickups, choice frequency and milestone conditions remain to be designed. Clearing or sealing a source still changes access and pressure, but a resolved stage no longer automatically defines the only ordinary award. Preventing a release gives safety and access; any additional reward for avoiding that fight, including an early seal, remains open.

Retreat preserves the temporary power already earned until the expedition ends. Leaving and re-entering a room does not by itself count as a new expedition. Reopening a seal or dying is not itself an ordinary fighting reward. Completed work keeps its owning persistence rule.

**Rhythm.** The intended climb begins during ordinary travel fights, changes the way the player handles denser crowds, and reaches larger transformations at major horde milestones. A new expedition renews both the opposition and the opportunity to grow, even on a route used before. Exact quantities and intervals are open. **How it could fail:** frequent choice screens interrupt the fight; growth arrives too late to affect it; or a milestone transformation feels like a reward after the exciting part rather than a new way to tackle what comes next.

- **Temporary combat upgrades end on every return home.** Unchosen temporary offers expire too. Each expedition starts a fresh climb toward spectacular power.

- **Combat areas refill for each new expedition.** Renewed fighting supplies fresh temporary growth after living returns and revival alike. Previously defeated crowds and previously earned temporary awards do not leave later expeditions with permanently spent combat routes.

**A familiar route, a new climb.** You return with a useful component after clearing the pressure hall. On the next expedition your temporary upgrades are gone, but the component is still yours and the door you unlocked stays open. Fresh enemies make the route a place to grow again. A permanent seal still blocks its former source, so the renewed encounter needs believable remaining approaches rather than reopening your completed work. How populations occupy these altered routes is the next placement task. The route should offer useful growth before its major encounter while retaining a viable approach for a player without a particular temporary upgrade. [Hordes and Builds](/Hold%20The%20Flood/Hordes%20and%20Builds) describes the intended power climb.

[Combat And Enemy Roster](/Hold%20The%20Flood/Combat%20And%20Enemy%20Roster) owns each creature's warning, action and recovery. In a crowd they play distinct parts. **Pressers** are the slow majority that fills the lane. **Flankers** are the fast packs on side routes. **Callers** wake the next stage. A **Boltspitter** demands a ranged line, a **Clampcrawler** occupies the control you are working, and a **Veilbearer** briefly hides the crowd behind it. Three special creatures — **Bellback**, **Shutterback** and **Glass Siphon** — change force, cover or your oxygen clock enough to deserve a featured entrance.

The balance gallery is broad, and it is the right kind of room for a big fight. As you enter, a Bellback plants itself across a fixed rib, its chest filling for a pressure wave, while the two feeding mouths at the far end of the gallery are already crowded. The station's own machinery keeps time around you. A Breath Bank draws across one lane on a three-beat rhythm, and a balance chamber's two plates tilt toward whichever side carries more weight.

In the quiet after, the chamber is still live. Freeing one rib takes two cutter releases, each a job that stays done once finished, and seating the pin then fixes that rib for good while the other still swings. On the far wall a mark matching the sample counter turns an old record into a lead.

**How it could fail:** three rhythms at once become unreadable, and the player dies to something they could not see coming.

- Target overrides and aim assistance, including whether nearest-visible stays the default.

- Field healing and lasting injuries are not yet designed.