It was popular among dwm/i3 users, and I have forgotten it :(
I was a fan of MacOS performing searches with Command + Spacebar, so on Linux I scripted a similar popup-prompt that would open Firefox and feed my input to this search engine.
!w filter bubble
will take you directly to Wikipedia... [DDG offers] 13,505 bangs and counting...”Searched for "Video Hub App" and it didn't find my website :(