How to play

Start with the default crowd and let it move for 10–15 seconds. Then change one thing at a time and compare what happens.

Find your starting point

1. Find the flow: watch a circle pit organize around its preferred route.
2. Beautiful disorder: compare independent headings with coordinated motion.
3. Room to move / Close encounters: explore how spacing changes contact between people.
4. Take the energy away: see what happens when active steering stops.

Change the crowd

The sliders change crowd size, preferred speed, intensity, alignment, and personal space. Changing crowd size restarts positions; the other controls take effect immediately. Circle mode lets you choose clockwise or counterclockwise motion.

Look inside the motion

Turn on velocity arrows to see direction and speed, contact forces to see pushes, or trails to follow recent paths. The density overlay counts particle centers per square meter; it is not a danger map.

Click or tap a person to inspect their mass, velocity, and forces. You can also choose a person in the inspector or focus the concert floor and use the left and right arrow keys.

Pause, replay, compare

Pause freezes the simulation so you can read the force table. Slow motion runs at one quarter speed. Reset restores the same initial arrangement; New crowd changes it. The page starts paused when your device requests reduced motion.

A useful experiment

Let a circle pit settle into motion, then turn self-propulsion off. Drive and active steering disappear, while contact and damping remain. Watch the kinetic energy fall. Setting preferred speed to zero is a different experiment: avoidance may still reposition people while propulsion is on.

These are experiments with a simplified model. Do not use the results to plan real crowd sizes, safety measures, or venue layouts.