I didn't get this right from the start, but this is a fork of fish(shell), which has been around for quite a while:
http://ridiculousfish.com/shell/beta.html
"Welcome to our fork of the fish shell, a command line shell like bash. Its working name is fishfish, but I hope eventually it will just be fish!"
Looks interesting. I expect my fingers will be even more confused than ever switching machines now (they've never learned that Alt-3 isn't # on linux or that middle-click isn't paste in Putty)
The ambition is quite reasonable as work on the fish shell itself has petered out, there was a recent dead cat bounce after a long fallow period, but it seems to be back to stasis there.