If you are wanting to use Helios and have Unity 5.4 beta there is some good news for you.

The issues that existed with the previous versions of the beta seem to have been cleared up and Helios is working just fine in Build 21

Helios 3D for Unity is now live on the Asset Store and can be purchased  at the special introductory price of $18.00 until the beginning of July 2016.
Get It Here

Just wanted to say thank you to all of the beta testers who helped get Helios ready for release.
You really helped push the envelope of what Helios could have been.

Helios has been submitted to the Unity Asset Store for review and should be available for purchase by June 18th 2016.