For the past 8 years, League has been using a patching system called RADS (Riot Application Distribution System) to deliver updates. RADS is a custom patching solution based on binary deltas that we built with League in mind. While RADS has served us well, we felt we had an opportunity to improve some key areas of the patching experience. We knew we could deliver updates much more quickly and more reliably by using a fundamentally different approach to patching, so we set out to build a brand new patcher based on content-defined chunking.

Hey there, my name is Riley “WhoaNonstop” Howsden, and I’m a Data Scientist who works on League of Legends, focusing mainly on personalization. Over the last few years I’ve been a part of the launch team for “Your Shop,” a product within League that creates personalized offers for every player around the globe. Data scientists like me work with engineers, analysts, artists, and publishing to create experiences that players love. From matchmaking and player behavior to artificial intelligence and game balance, data science is a key contributor for many initiatives at Riot. 

So, why do Bug Blogs? Well, at Riot, we believe that a fundamental component of the development process is understanding that failures can and do happen. We make mistakes because we’re humans, and humans are far from perfect. And that’s okay! What’s important is to recognize failures for what they are, work to understand why they happened, learn from them, and make needed changes based on those learnings. That’s how we grow and that’s how we get better.

Hi, my name is Eric Friedman, and I’m a Software Engineer who has been working on League of Legends for 8 years, focusing mainly on gameplay systems. For the last several years, I’ve been working in the Player Immersion and Expression (PIE) initiative, bringing you skins like Elementalist Lux and personalization options like Emotes. If you’re interested in how Elementalist Lux was implemented, check out our previous article. I’m excited to bring you another article about an ultimate skin, Gun Goddess Miss Fortune, and the technology it took to bring her to players.

Hey folks! We’re going to take a trip back in time. The year is now 20xx, and we’ve decided that it’s finally time to send one of League of Legends’ most long standing, revered or reviled features (depending on who you ask) to the meme graveyard.

That’s right - it’s time to retire runes and masteries.

Hi, I’m Tony Albrecht, an engineer on League. I’m back with some more performance goodness. In the previous article, we tracked a slowdown reported in an LCS game and an issue with Swain that was first reported by players. For this article, we’re stepping back a little further and looking at how we can measure the aggregate performance of League over an entire region, notice a dip, and then narrow down the cause. In this case, we chased a 2ms per frame drop in performance to a single missing ASCII character in our code.

Hey there. I’m Stephen “Riot FloofyRice” Zhang and I’m a technical developer in QA on the Content Efficiency team, which focuses on building internal tools. I want to talk about our efforts to clean up one of our bigger problems at Riot: data debt.

Hi, I’m Tony Albrecht, an engineer on League. You might remember me from such articles as Profiling: Measurement and Analysis and Profiling: Optimisation where we looked at how we find and optimise performance bottlenecks in the LoL code base. In this article, we’re going to take a step back and look at how we detect and then fix real world performance issues that slip out past our QA and monitoring systems and escape into the wild to plague you, The Player.

Combating cheats is an ever-evolving arms race. The scope and complexity of cheat development grows every year along with the stakes in online gaming. The pressure is on for game studios to level up when it comes to detecting and preventing bad actors. I’m Michael “Perma” VanKuipers, and I used to be one of those bad actors; I spent over a decade developing cheats for various games and earned the ire of at least one large game studio in the process. These days I work on Riot’s Anti-Cheat team, helping secure League of Legends from scripts, bots, and exploits.

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.