This program uses the web camera to capture a change in pixel brightness. The coordinates of the bright pixels then become new particle emitters. Controls on the left side of the window allow to adjust a behaviour of the particle system. It is also possible to add a collision and flocking behaviour to the particles.
In my bigger project about which you can read in my blog I created a flame for a candle using a particle system. In Unreal Engine 4 the light from the particle system is not correctly interpreted by the subsurface scattering that I used in the skin and candle materials. Because of this I had to create a separate light source on top of the candle to make it look more realistic.