Endless Gloom - Short personal project. It's got a couple issues, but overall I'm happy with it.
I used Houdini and Redshift, as usual. It's a meshed smoke sim. The loop was trickier than I originally expected. To "catch" the smoke as it travelled I had to scale up the collider object, in doing so the the skull shape at the end had a higher poly density than at the beginning (the smoke grid is uniform, but in filling the larger volume at the end it had more detail) So I had to render two passes and do a little comp work to make the loop point more seamless.