Explore the architecture and implementation of Riot Games' League of Legends messaging system in this conference talk from Strange Loop. Dive into the challenges of building a scalable, real-time messaging service capable of handling hundreds of millions of players. Learn about state changes, stateful services, and the importance of linear scalability and fault tolerance in large-scale distributed systems. Discover how the Riot Messaging Service enables backend services to reliably communicate with players in real-time, and follow the journey from concept to production servers supporting 10 million player connections on a single box. Gain insights from software architect Michal Ptaszek's experience in designing and implementing highly concurrent, fault-tolerant systems for one of the world's most popular online games.