Growth — a small number of spore points each seed 2–4 hyphal tips. Every tick a tip advances one step along its heading, wandering by a small random jitter (real hyphal tips wander a few degrees per step rather than growing perfectly straight). A coarse occupancy grid records local mycelial density; a tip that grows into already-dense tissue dies — the same density-limited principle behind diffusion-limited aggregation, standing in for local nutrient depletion. With probability set by the branching slider, a tip forks into two: the new heading is offset by an angle drawn from a Gaussian centered on 35° (σ≈15°), matching the branching-angle statistics reported for real fungal hyphae.
Bioluminescence — every hyphal segment's light output follows Michaelis–Menten enzyme-saturation kinetics for the luciferin–luciferase reaction:
rate = Vmax · [S] / (Km + [S])
where [S] is the luciferin substrate concentration slider (µM) and Km is fixed at a literature-typical 5 µM — so light output rises steeply at low substrate and saturates once [S] ≫ Km, exactly like a real enzyme-limited reaction. That rate is then gated by a circadian term, 1 − 0.85·max(0, cos(2π(hour−12)/24)): a sinusoidal suppression that is near-zero at midnight (full glow) and strongest at noon (glow suppressed to 15%), reflecting the documented pattern that many bioluminescent fungi (e.g. Neonothopanus species) glow far more at night. Younger hyphae also glow brighter than old growth (luciferase activity decays with an exponential age term), so the growing front of the network is visibly brightest.
- Branching probability — controls how bushy vs. sparse the network becomes.
- Substrate [S] — controls how close the reaction sits to its Vmax saturation ceiling.
- Time of day / day-cycle length — controls the circadian gate driving day/night glow intensity.