The light radius is a circular gradient image as a sprite which follows your character (pinned perhaps). This gradient could be used on a layer colored black, and you would use that gradient as a mask to see through the black layer.
Your character also needs a shadow light object to follow it (pinned perhaps), and all the boxes need a shadow caster behavior. Make the shadow casters cast on a layer above the circular gradient light radius, and the effect should be complete.
Perhaps see this for guidance on the light radius effect: