Particle Life Simulator is a free, browser-based sandbox for exploring emergent particle behavior. Every dot follows simple attraction and repulsion rules with nearby particles, and by changing the starting preset or a single control you can watch those local reactions grow into clusters, trails and new patterns.
The site says you can play for free in your browser, with no download, and that it works on mobile. It offers eight presets to compare: Bloom, Orbit, Cells, Swarm, Rings, Maze, Bridge and Void. You can adjust attraction forces and explore eight bounded controls, from damping to family count. There is also a 3D depth mode you can orbit with drag, wheel or pinch controls, and a lighter 2D colony that uses tap, drag and pinch gestures on touch devices.
Pointer disturbance injects energy into the colony so it can reorganize. The page also explains what you are seeing: stable clusters mean several families found a temporary balance of attraction and repulsion, while moving trails usually appear when one family chases another faster than it can settle.
According to the homepage, the simulator runs locally in desktop and mobile browsers and requires no account or app download. It is aimed at anyone curious about particle life, emergent behavior or generative simulations who wants a quick, hands-on browser experiment rather than a full research tool.