About the author:
Matthew Macfadyen, 6-dan – many times UK Go champion
There was a variant called joker go.
This was invented by Patrice Gosteli just before the 1984 European in Porrentruy. He printed two copies of a set of 15 cards, each card had a group of two or more patterns of go stones (e.g. kosumi, ikken tobi, empty triangle, bamboo)
The original rule was that you played normal go on a 19×19 board but each move you could choose to play one of the jokers (playing all the stones in the pattern together). You could play each card only once.
But by the next year in Terschelling the game became very popular played on a 13x 13 board and with the cards face down, so you could choose to play a joker but it was luck which one you got – if there was a legal move it must be played even if filling in your own eyes.
Later a german guy called Lothar Teikemeier made a set of cards which had all sorts of special powers, like changing the colour of your opponent’s stones. I did not like this because the cards were too powerful, and with some luck the whole game could collapse in one move. It never became very popular.
There have been a few other attempts to make go variants but none seem to be nearly as interesting to play as the real game.