I'm not talking about the shadows but about the glowing/lighting effect on the crystals and the torches.
Anyone got any clues?
I've never used Unity, so I don't know what it has to offer for this specific problem, but I would create this effect with one of these methods:
Here is what I mean by "glow texture"
Create a new material, with shader Sprites > Diffuse.
Select all the objects you want to react to lighting, go to their Sprite Renderer and change the material to the one you just created.
Create a point/spot light at Z=-1 and you should see the light.