Retrogen

Most new world-generation content only shows up in areas the player has not explored yet. Retrogen instead processes chunks that already exist and are loaded, adding compatible ores and structures from mods installed later. A player can keep using an existing world without travelling thousands of blocks to find the newly added resources.

Chunks are queued when they load and handled only after loading. Retrogen caps both the number of operations and the processing time spent during each server tick. It stores processed content inside the chunk, so the world keeps its generation history and the same ore or structure is not placed twice. The configuration file is created automatically, and Retrogen picks standard modded ore features from allowed namespaces on its own.

Retrogen is a world-generation mod that runs on the server. A dedicated server needs it installed, while players can join without it. Single-player worlds place it in the client's mods folder. Files are published separately for Fabric and NeoForge, both for 1.21.1, and the Fabric file needs Fabric API. The mod is not open source and is released under All rights reserved.