Free-to-play games often use an interesting feature of the human brain: most of us are inclined to add value to items and events that are in some way limited, be that in time, quantity or availability.
In this article for GamingonPhone, we talk about limited in-game events in one of our top games - Gold & Goblins.
If you want to look behind the curtains of designing in-game events in mobile games - you are welcome to read this article written by Elena Bugakova and Elizaveta Khilkovskaya, Producers at AppQuantum.