At 12:30 today, Hearthstone fans went into a tizzy when the official twitter account posted a brief video clip of a fourth, unlabeled button appearing on the Hearthstone UI along with the brief message “Huh, that’s new!”

There have been theories for a while among the Hearthstone community what the space would be used for, and the appearance of this button has only reignited passions. Several theories say that this could be used for a new game mode. Fans are suggesting modes including 2v2 matches, player tournaments and custom game lobby creator, but the possibilities are limitless. Official Blizzard channels have already confirmed that there will be no co-op modes, and that this button won’t be used to open the in-game shop. Hearthstone recently announced that alternate hero skins would be available to players for $10, which this new mysterious button could relate to.

What this mystery fourth button means is a mystery for now, but we’ll update you as soon as Blizzard spills the beans!