Masahiro Sakurai stated in the recent smash direct that King of Fighters/Fatal Fury character Mai Shiranui won’t appear in Smash Bros. Ultimate. This was due to CERO threatening to raise the rating, but the English translation stated it was because “the series is for good boys and girls.”
Fans decided they didn’t like that and have been placing tributes to Mai in the form of stages, mii characters and more into the game as a protest.
See a gallery of these here