Each point represents a single dark matter particle from the ds14_a simulation. The color of the particle is based on the radial velocity with respect to the center of mass of the halo being shown. Blue is moving towards the center. Red/orange is moving away.
You can use your mouse to control the view: click-drag will change the right ascension/decliation, double click zooms in, and mouse scroll-wheel zooms in and out.
The following key bindings are also available: left, right, up, down (scroll the view), +, - (zoom), r (reset view).
WebGL and the three.js library are used for rendering.