At Pocket Gamer Connects Helsinki 2016, Simon Hade, COO of Transformers: Earth Wars developer Space Ape Games, gave a talk on how the studio uses in-game events to drive its revenue.
Hade defined in-game events as a "system that sits on top of the core game", and provides different objectives and tweaks to existing gameplay.
One thing that pushes these events is the "social drama" involved with alliance-based events, in which some players will peer pressure others into playing the game so the alliance can get better rewards.
Hade also touched on the timing of events, suggesting that developers study how their events are affecting retention and planning their live event launches accordingly to keep players coming back.
You can see all our videos from Pocket Gamer Connects Helsinki 2016 in this YouTube playlist.