A damaged facility releases an apocalyptic contaminant. Rising
plume particles drift downwind, convert into fallout, and land on
a grid of terrain cells — each cell tracks its own contamination
level (green → yellow → hazard purple). Contamination decays with
the substance's half-life, sped up by emergency cleanup response,
and — for the more mobile substances — spreads a little into
neighbouring cells each tick, the way real fallout, chemical
plumes and biological agents differ in how far and how fast they
travel from the source.
C(t+dt) = C(t)·(1 − λ_eff·dt) + ΔC_deposit + D·Σ(C_neighbour − C)·dt
λ_eff = ln(2)/T½ · (1 + k·response)
Exclusion radius = max distance where C > 0.30
- Release intensity — how much contaminant escapes the source per second.
- Wind speed — how far and how directionally the plume drifts before falling as deposit.
- Emergency response — cleanup/containment effort; multiplies the effective decay rate λ_eff.
- Substance — radioactive (long half-life, low spread), chemical (medium half-life, medium spread), biological (short half-life, high inter-cell spread — it behaves like a contagion).
This mirrors real hyper-extreme pollution incidents (Chernobyl-
scale radioactive fallout, major chemical plant releases,
runaway biological contamination): total-area exclusion zones,
international coordination on containment, and years-to-decades
of ecological recovery once the source is controlled.