Normal is a screensaver for macOS 10.12+. It applies a configurable Gaussian blur to whatever is on the screen. That's it. I wrote it in 2017 when I was meant to be focusing on something else.
Download the screensaver from the releases page and double click to
install it. The screensaver is code signed with my Developer ID certificate
spctl) but because Normal is a bundle not an app, Gatekeeper
might complain anyway.
Note macOS sometimes has issues with screensavers written in Swift. If you get an error when trying to use the screensaver, reinstalling it and/or restarting a few times should make it go away.