Hodgepodge Machine

Martin, Odlyzko & Wolfram (1984) — discrete reaction-diffusion with spiral waves

States (k) k = 20
Infection (k1) k1 = 2
Recovery (k2) k2 = 3
Infection rate g g = 4
Speed x4
The Hodgepodge Machine is a CA where each cell has state 0 (healthy), 1..k-1 (infected), k (ill). Infected cells spread based on neighbor counts. The result: spontaneous rotating spiral waves — a discrete Belousov-Zhabotinsky analogue.