The game has an event with the Piggy Bank mechanic.
It would seem that everything is as usual—the player goes through the levels, accumulates currency in the piggy bank, and opens it when a sufficient amount of in-game currency is accumulated.
So what’s so special about it? The accumulated currency goes to the player for free.
Engagement The player needs to earn a minimum of 100 coins and a maximum of 200 coins to break the piggy bank. For completing each level, the player receives five coins, which means that in 24 hours (the duration of the event), the player needs to go through 20-40 levels. This leads to an increase in the length and frequency of sessions.
Monetization The player spends more to complete levels than they get. To pass so many levels, the player needs to spend boosters and buy additional steps.
The event takes place once a week on a weekend when the player has the most time to play.