After nearly a year and a half of work, a small team of modders released a multiplayer mod for The Legend of Zelda: Breath of the Wild this week to help YouTuber PointCrow meet his $10,000 challenge set for November 2021. The mod is currently available via Discord, and allows up to 32 players to travel around Hyrule together, sharing progress and competing in several custom game modes added by the mod. Lead modder AlexMangue told me that PointCrow (opens in new tab), who regularly does speedruns and makes videos about "Breath of the Wild," was heavily involved in the mod's development.

"He didn't just put a 10K bounty on it. He not only put a 10K bounty on it, but he also helped us financially throughout the project."

"He was also the director of the project in a way, creatively, bringing ideas of what to work on next.

So far, the mod can synchronize so many things between players, including player location, weather, time of day, enemy health, and progress on discovered towers and shrines. However, it still lacks a few key features to feel fully complete, such as synchronization of enemy AI. In the mod's current form, other players can see that you have damaged an enemy, but it does not move the same on their screen as it does on yours. This inconsistency highlights the difficulty of completing a mod like BotW Multiplayer when you don't have access to the game's code.

"Nintendo ships the game code without symbols, so we didn't really use the game code by itself because we can't actually read it. This main part is similar to how cheaters work in other games." By injecting its own code into the emulator, it gains access to information stored in the computer's RAM for processing by the emulator. This allows us to look for specific information in memory, such as the player's position or rotation. This is the extraction part, just getting the data we need to send to the server we have coded.

After the server gets the data from each player, it parses some of it and relays it to the other players. This is where things get crazy. We use NPCs that are actually in the game and make them look like links; once we spawn an NPC, we look for the same information as before and change the NPC's position, rotation, etc.

Some of the code in Breath of the Wild is easy to parse from system memory, while others are not. For example, enemy health is a simple value, but AI is naturally more complex, and according to AlexMangue, there are several things that need to be prioritized after this 1.0 release.

Getting to this point has been a major team effort, with development work by modders Ahrdoc and Sweet and contributions from many other established Breath of the Wild modders. For that core team, this week's release was especially significant. Alex Mangue said, "It was the first time anyone on this team had done a release, so it was pretty cool." 'It's so happy to see how cool the community is and how many people are helping each other out.'

Installing the mod is a fairly complicated process that requires running "Breath of the Wild" on the Wii U emulator Cemu (the Switch version of the game is not supported), patching the game, and connecting online. mod server players are helping to simplify at least part of the process by setting up a server so that anyone can play without having to host the server on their own local machine. For the brave and enthusiastic, see this installation guide.

There are other fun videos of this mod by a German YouTuber playing a custom hide-and-seek game mode with five other players.