Limited time offers with unnecessary urgency.
"Store rotates items on sale and locks. Certain events and modes limited to 24 hours every week or two."
"there are always limited time events, and they make their cute images sad if you dont complete or win them"
"There is a limited time offer for new players but that doesn't really do much. However there has been a few skins and pets, usually from crossovers that have been limited."
"There’s always a different limited time event with exclusive prizes you can only get through that event."
"Nearly everything in this game is urgent. The worst example is the events, as their timeframes are on average 2 days long. F2P players are guaranteed to never be able to complete these in full, and even players who spend money on in-app purchases aren't guaranteed success, either, as many events are based on luck."