I have attached a registry patch file that allows windows users to right click on any folder and open it with unity.
Just download the attached OpenWithUnity.txt file. Then rename the file extention from .txt to .reg. You can then right click the file and select merge.
NOTE: If you have installed unity other then the default location C:\Program Files (x86)\Unity\Editor\unity.exe. You will want to edit the file in notepad before merging.
ALSO NOTE: Merging under windows 8 is immediate. Earlier versions of windows may require you to close Windows Explorer and re open windows explorer for the option to become available when right clicking a folder.
I’ve red the file, seems legit. But I think it would put this option on every folder, which would be annoying.
Plus it sucks that they didn’t show how to undo this.
I’d rather stick with opening projects through Unity.