How to play Picky Pixie

How to play the new ‪@ButtonShy‬ deduction game.
Each player gets a turn to be the pixie, making a secret rule about which groups of flowers they'll accept. All the other players take turns "making an offer" of a group of flowers from the top of the deck.
Call a guess to allow EVERYONE to guess the secret rule. If 1+ players guess it correctly, they get 1 point for every card left in the deck. And the Pixie gets 2 points for every time a guess was called.
Once everyone has had a turn to be the Pixie, the game ends.