1. Clash of Clans is a popular free-to-play mobile strategy game where players build villages, gather resources, and attack other villages.
2. Though the game is free to play, it makes money through in-app purchases of gems using a freemium model.
3. The game's financial success is based on a three-layer ecosystem where different layers serve different purposes to create scale, commitment, and profit. The first layer reaches a wide audience, the second invites player investment through base-building, and the third offers tools that can be upgraded through optional in-app purchases.