Idea for the game: Events featuring ghosts with certain attributes that will get specific boosts for a limited period of time. The duration can be weekly, monthly, or it could vary from one event to another. Give the event a catchy name, have it announced on social media and make it visible in game. For instance (as we don't know the exact game mechanics just take these numbers as an example):
"You came to the wrong neighborhood!" Ghosts with grills and/or chains deal 20% extra damage.
"Happy St. Patricks!" Any ghost with a green attribute (green body, green background, green hats, etc.) gets +15% BNB rewards.
"Is that all you got?" Ghosts with an uninterested look and frown mouth take 30% less damage.
Combinations are endless. Benefits I see from these events: