Mattimeo78---
So sorry. I just read your post.
Like you, after I reinstalled, Impulse did not recognize the game. I had to figure out how to make Impulse point to the right directory (select "More" from the bottom right, then "Open application folder" and point it to the install directory. For some reason, the first time I installed the game, it loaded to my "Program Files (x86)" directory but, the second time, it loaded to my "Program File" directory. Most odd. I did, however, choose the basic versus the advance install the second time, so maybe that caused that.
I know you solved your problem, but for anyone else...
Before I messed with my registry, I made sure there was no reference to Elemental in my "Uninstall a program" area. I also made sure there was no reference to my Best Buy add-on content about Titan's Blacksmith by uninstalling it in Impulse. Then, I opened my file explorer and made sure there were no Elemental directories or files in any Stardock or Impulse folder on my hard drive. I had to manually delete an Elemental directory with its remaining files that were not removed by the uninstall. Only then did I reboot and only then did I search my registry.
For me, there was only one folder related to Elemental:
HKEY_CLASSES_ROOT\Installer\Products\[elemental key folder]
My Elemental key folder name was a 32 digit alphanumeric code. Heck, every folder under Products seems to be named like this.
I just deleted the whole folder, and closed the registry.
But, unless you don't mind possibly destroying your registry, I do NOT recommend messing with it. Not for the faint of heart.
Anyway, Stardock did respond to me. They sent me some utility called SDSupport.exe that I'm supposed to run and send back a zip file it creates. But I didn't have to do this.
Surprisingly, Elemental is much more stable after the second install. It was almost unplayable the first time. I can't remember in which order I installed the Best Buy add on content (before or after the patch), but however I did it the second time may have had an effect.