Why Fortnite’s Playground Mode Didn’t Work at Launch

Fortnite’s Playground Limited Time Mode didn’t work as well as intended when it launched weeks ago, and Epic Games is now back with an explanation of what went wrong.

Playground is the sandbox-style mode that players have been asking about for some time now, a mode that lets everyone build as much as they can within an hour. Only four people are allowed in one game at a time, so you can keep the buildfest organized with the squad members that you want to be included. That was the idea, anyway, and though it worked later on, that wasn’t the case in the beginning. Breaking down the technical aspects of the situation that caused a hangup with the mode, Epic Games started by explaining how the matchmaking system works.

“Our matchmaking is built on something called the Matchmaking Service (MMS), which is responsible for facilitating the ‘handshake’ between players looking to join a match and an available dedicated server open to host that match,” Epic Games explained. “Each node in the matchmaking cluster keeps a large list of open dedicated servers that it can work with, randomly distributed by region to keep a roughly proportional amount of free servers for each. Players that connect to MMS request a server for their region, MMS assigns that player to a node, and the node picks a free server for the requested region from its list.”

But because of Playground’s smaller game sizes that only allowed four players in each instance of the game mode, Epic Games “had to use 15 times as many servers as we had been running for the other modes.” This difference from the normal server setup didn’t play well with Playground, Epic Games said, and inevitably resulted in a “feedback loop that eventually cause[d] the system to grind to a halt.”

After identifying the problem, Epic Games came away with a solution and an upgrade that’s being brought over to the main game’s servers.

“Once we identified the root of the problem as the exhaustion of sessions from local lists, the solution was to give the cluster the ability to bulk rebalance sessions from other nodes to ensure repeated lookups were not necessary. With the system constantly shifting regional capacity from nodes with an excess to nodes that might be running low, the odds of a node running dry for a particular region and having to search outside its local list have been drastically reduced. While not an issue right now in the primary Fortnite Battle Royale game modes, this is an upgrade we are bringing over to the main MMS cluster as well to future-proof the system.”

You can read about Epic Games’ “learning experience” along with a full technical breakdown here.