If you have watched some of the EEVEE demos in Blender 2.8 Beta all of them have one thing in common. They have the volumetrics and dim lights in the background. EEVEE is making this possible. It is not with a high end quality but for an effect like volumetrics and rendering in real time it is doing an amazing job.
Adding volumetrics is easy. There is a dedicated node for that.
The volume scatter node!
Go to the node editor, now called shader editor. Then just next to the shade editor tool select the world tab to enter the world settings. Shift A to add the node. You can search it from the box, just write volume scatter.
Connect this node to the volume slot from the world node.
Here is the difference with gif :)
Cool!
It looks even better in live.