The price of determinism is eternal vigilance.

I’m Rick Hoskinson, an engineer on the League of Legends Core Gameplay Initiative, and this is the final article in the “Determinism” series. Previously in this series, we explained the broad strokes required to achieve determinism in the League of Legends game server. However, there remained the task of tracking down the remaining divergences in legacy code while building maintainable systems that would ensure future divergence regressions could be found and fixed. Thoughtful implementation of these systems allows us to sustain Project Chronobreak features without dedicating a full-time team.

In this final article, we’ll dig into how we detect divergences and fix them.

Hi there. I’m Bill “LtRandolph” Clark, and I’m the engineering manager for the Champions team on LoL. I’ve worked on several different teams on League over the past years, but one focus has been consistent: I’m obsessed with tech debt. I want to find it, I want to understand it, and where possible, I want to fix it.

Hi, I’m Rick Hoskinson, an engineer on the League of Legends Core Gameplay Initiative, and I’m here to talk about how we gave ourselves the power to turn back the hands of time in League of Legends. In this series of blog posts, I hope to give you a glimpse of what that work looked like, juicy technical challenges and all.

Taking the League of Legends game server from a nondeterministic process to its current state required almost a full year of effort from multiple engineers. As a side benefit of this effort, we holistically improved the codebase’s robustness, discoverability, and maintainability. We removed swaths of dead or redundant code and created new opportunity spaces for gameplay exploration.

Hi, I’m Rick Hoskinson, an engineer on the Deterministic Disaster Recovery team, and I’m here to talk about how we gave ourselves the power to turn back the hands of time in League of Legends. In this series of blog posts, I hope to give you a glimpse of what that work looked like, juicy technical challenges and all. In this first post, I’ll introduce the problem and how we chose to solve it. 

Hey there! My name is Michal 0xDEADB33F Ptaszek, and I’m a software architect at Riot. Today I would like to talk about communication. But not the kind of communication you’re probably thinking of. I want to talk about the other, more exciting kind of communication: LoL players communicating with chat servers during a tense game; authentication servers communicating with the LoL client on login; microservices that route state changes between clients in the middle of the night - you know, that kind of communication.   

Hi! I’m Jules Glegg, a Software Architect working on the League client update. We’ve been fielding a lot of questions about how the updated client’s Javascript/HTML/CSS works, and there’s a huge amount to cover there. I’m here to give a very broad overview of the most interesting parts of our UI architecture - we won’t get to cover every bolt and weld in this post alone, but we should get a good feel for the general shape of things.

If you see something you want to know more about, drop a comment and let us know! For now though, let’s dive in.

This article is the third in a multi-part series on the Riot Games API. As discussed in our second article, the API is fronted by the Zuul proxy server developed by Netflix. We chose Zuul because Netflix built it to handle an enormous amount of daily traffic, so we knew we could trust that the code was battle-tested and production-hardened.

Hello all, Leigh Estes, aka RiotSchmick, here. I’m a software engineer at Riot Games working in the Service Availability initiative. Our first article on the API covered our goals, the responsibilities of the Developer Relations and Developer Platform teams in the API ecosystem, and some high-level details about the technology we used in building our API solution.

Hi, my name is Jeff, and I work out of the Riot St. Louis office on the Always Available Friends team. We recently released the League Friends app for Android and iOS to give players a way to connect with their League friends outside of the game.