Game of War: Fire Age, developed by Machine Zone, was one of the first mobile massively multiplayer online (MMO) strategy games to popularize kingdom-building mechanics. Released in 2013, the game became known for its complex alliance system, where players could form powerful coalitions to wage war against rival kingdoms. The core gameplay revolves around resource management, city building, and warfare, with players expanding their empire while defending against other player's attacks. Game of War also introduced real-time chat functionality, enabling players to communicate and coordinate with their allies in real-time.

Game of War's success lay in its deep, strategic gameplay and the social element of working with others to dominate the game world. The game was known for its high level of competition, with top players spending significant amounts of money on in-game purchases to stay ahead. Its aggressive monetization model, while controversial, contributed to its financial success, making it one of the highest-grossing mobile games of its time. Despite being overtaken by other games in popularity, Game of War: Fire Age remains a significant milestone in the history of mobile strategy games, setting the stage for future kingdom-building MMOs on mobile platforms.