Vicsek Model (Active Matter)

A minimal model of flocking. Particles move at a constant speed and align their direction with their neighbors within a radius, plus some noise.
In this ASCII translation, arrows (`>`, `<`, `^`, `v`, etc.) indicate the heading of each particle. The color (from dim green to bright yellow) indicates how strongly aligned a particle is with its neighbors. Lower the noise to see them phase-transition into an ordered flock.