Finnish gaming company Supercell is a $3 billion company largely in part to the success of its game Clash of Clans.

Clash of Clans is a strategy game that is free to play, but some people end up paying hundreds of dollars on in-app purchases and upgrades. 

So it’s no wonder why Clash of Clans is among the top 10 grossing apps in the iTunes Store, according to AppData.

source: businessinsider