Verdant Drift

Open the playable simulation

A single-file Three.js artificial-life island. Every seed builds a new heightmapped island with meadows, forests, rocky highlands, sandy shore, and shallows. Three ecological roles interact through explicit rules, reproduce with uniform-crossover + gaussian-mutation genomes, and visibly change body type over minutes of real time as trait drift accumulates.

Run

Open index.html directly in a desktop browser (Chrome, Safari, Firefox).

If your browser blocks ES module imports from a file:// URL, serve the folder:

python3 -m http.server 8080

Then open http://127.0.0.1:8080/.

Controls

• Drag to orbit · scroll to zoom · right-drag to pan.
• Click any organism to inspect its traits, state, energy, lineage, and decisions. The inspector follows the creature until it dies.
• Speed slider / preset chips to pause, slow, or accelerate the sim. Keyboard: space to pause, 1 2 3 4 for 1× 2× 4× 8×, 5 for 0.5×.
• Seed input + Go reproduces a specific run; New island rolls a random seed; Reset reruns the current seed.
• How it works opens an in-app explainer of the genome, behavior FSM, reproduction rules, day/night effects, and performance shortcuts.

What's in the sim

• Leafers (green) — herbivores. Graze meadow plants, flee Stalkers, pair up and reproduce when well-fed. Body grows legs and ears that scale with speed and sense; armor gene grows visible spines.
• Stalkers (red) — predators. Hunt Leafers and Sprites. Get +20% speed and up to +60% sensor range at night, so their nocturnal gene pressures prey to invert their schedules.
• Tide Sprites (blue) — shoreline foragers. Eat algae and carrion, leave nutrient wakes that help nearby plants regrow. Fast and skittish.

Each organism carries an 8-gene genome (size, speed, sense, metabolism, armor, aggression, fertility, nocturnal). Genes affect both behavior weights and the visible body (scale, leg length, head size, tint, spines, fin length). Offspring inherit uniformly-crossed genes with gaussian mutation (σ ≈ 0.08), so within 5–10 minutes of accelerated time you can watch size, speed, sense, and nocturnal traits drift in response to who actually survives to breed.

Inspectable views

• Simulation — live 3D island with HUD, organism click-inspection.
• Populations tab — stacked population lines for all three species plus plants, plus a smoothed births-vs-deaths-per-minute chart for spotting predator-prey oscillations.
• Traits tab — per-species gene-drift lines (size · speed · sense + one species-signature gene) so you can see selection pressure act on the genome, not just population counts.
• Lineage tab — current snapshot + max generation depth over time.
• Events tab — birth / death / mutation / extinction log with timestamps.
• How it works modal — one-click explanation of the whole system.

Day / night

A simulated day is 120 sim-seconds (scaled by the speed slider). The sun and moon orbit the island; sky crossfades dawn → noon → dusk → night with stars visible at midnight. Night raises Stalker sense range and speed, suppresses plant regrowth, and encourages non-nocturnal species to rest. Nocturnal drift in prey populations is a real, observable outcome.