It is a first class quality shake and I have tried a lot of them. It is natural and organic and appears to use springs and dampers like real earthquake shock. I am adding this to my current game immediately because it adds a lot to anything in 2D just by being dropped in.
Thanks for giving something away of such amazing quality. I've bought a half dozen similar tools on the Asset Store and none of them came remotely close to what I wanted - this did and I got it free off Itch.io!! You're a generous person and it makes me want to do something similar in future if I develop a good trick in my own code.