Move the mouse to walk round the fire and click to throw on another log: a shower of sparks and a flare of light.
Three emitters (flames, sparks that bounce off the ground through a particle collider, and smoke), a point light whose intensity and reach flicker with a few waves out of step, logs whose emissive colour pulses, and the moon as the one light that casts shadows.
The logs you throw on exist from the start, hidden: a click happens outside the scene's body, where nothing can be created, so it only shows them.