# GOL-020: Shared Fever

Dense clusters catch a shared fever, move together by their collective compasses, then face ordinary Life during a mandatory break.

[Open simulation](https://100gol.com/experiments/020) · [Directory](https://100gol.com/experiments)

## What to explore

Make infection, rigid collective motion, and mandatory vulnerability visible.
Individual compasses should combine into body headings, with exact cancellation
resting honestly. Preserve Conway defaults even if long runs settle.

## Rules, update order and replay

Square Moore lattice, 80/120/160 square; diagonal contact counts. Toroidal default,
optional bounded edges. Living organisms own heading (0 NW, 1 N, 2 NE, 3 E, 4 SE,
5 S, 6 SW, 7 W), permanent rotation sense, private turn counter, infection turns
remaining, and break turns remaining. Grid positions own independent seeded birth
streams. Generation and previous-Step causal evidence are part of complete state.

Freeze occupancy and state. Eligible living cells have no break. Any eligible
living cell with at least the threshold number of living neighbors initiates
infection; all living neighbors count, including recovering ones. An existing
infection also seeds spread. Flood through the complete connected eligible
component immediately, before Life. Recovering cells cannot initiate, receive,
or relay infection. Existing clocks never refresh; newly infected cells receive
the configured duration. This explicitly uses whole-component knowledge, unlike
GOL-008's one-ring-per-turn propagation. Component IDs are temporary grouping
indices only and never choose winners or persist as organism identity.

Sum equal-length compass vectors across each infected body. Choose the nearest
of eight directions; zero or exactly tied result rests. Integer directional
histograms and exact arithmetic in Q(sqrt(2)) resolve ties without floating-point
or traversal-order priority. Every member proposes one identical one-cell shift.
Its own body's old positions may be occupied; any other frozen living occupant
blocks the complete move, even if about to die/move. Bounded edges block the whole
body. Among geometrically possible proposals, any shared destination rejects all
claiming bodies, with no retry, swaps, partial movement, or priority. Blocked and
resting bodies remain protected and their clocks advance normally.

Uninfected/recovering cells apply B/S at frozen counts. Accepted arrivals supersede
births. Frozen living departed sites receive no birth this turn. Newborns start
uninfected and first act next Step. Commit together, then surviving organisms
advance their compass clocks; the heading before the turn is used for voting.
Infection acquired on turn 10 with duration 3 protects turns 10,11,12; turn 13 is
the one-turn break, and a survivor is eligible again on 14. Density loss never
shortens infection; density/contact never extends it. Clocks are individual, so
later recruits can outlast older members. Bodies merge/split by current eligible
contact on the next Step. Break applies ordinary Life immediately; there is no
GOL-019 isolation exception. Death clears organism state; rebirth assigns fresh
compass/sense from the position's stream, with no inherited infection or break.

Reset rebuilds selected occupancy and every hidden layer from separate world and
compass seeds. Painting consumes a fresh local birth assignment; erasing clears
organism state and editing clears transient evidence. Compass cadence edits pause
and restart turn counters, retaining headings/field/infection. Other rule edits
pause and affect future actions; ongoing infection retains remaining time. Break
length is sampled on infection expiration. Applying presets uses these same rules.

## Reading the simulation

Canvas 2D; lime ordinary life, cyan infected, amber mandatory break, cream births,
with pale arrival outlines and coral blocked outlines. Simplified Color retains
binary occupancy while written inspection preserves the evidence. Select a cell
to outline its entire proposed body and targets and inspect neighbor count,
infection source, lifetime/break, body size, eight heading votes, resultant,
blocked reason, organism fate and exact next site. Compasses are private even
when members temporarily share a displacement. Mobile randomize/reset/play sits
after the stage guides and keeps the rail action.

## Reproduce a starting configuration

[Download example JSON](https://100gol.com/api/experiments/020/configuration). Import it using Share & reproduce in the simulation controls. It starts paused at Step zero. Files contain rules and initial conditions, not evolved boards or manual edits. See [format, limitations and automated access](https://100gol.com/agents).