WorldPlanner

WorldPlanner is a NeoForge 1.21.1 mod that lets you design a whole Minecraft world on a map before it generates. You paint the biomes, structures, terrain height, , lakes and roads, then hit "Generate" and get a world that follows the plan(get it? WorldPLANNER). You can also open the plan of a world you're already playing in and change it while you play.

It's still a prototype, so some things aren't there yet. More info on the project's documentation over at github

The basic idea

A plan is a square grid of cells. One cell is one chunk (16 x 16 blocks). A plan can be anywhere from 8 x 8 up to 1024 x 1024 chunks, so up to 16384 blocks on a side. Every cell holds a biome, and optionally a structure and a terrain height override. On top of the cells there are lakes, rivers, roads, mob and ore rules, and "chance" groups that leave things up to the world seed.

Plans are saved as .wplan files in a worldplanner folder inside your game directory. When you generate a world, the plan is baked into that world's save, so the world keeps working even if you later delete or edit the plan file(although if you remove the mod or the plan file, new chunks won't follow the plan).

If you need more info on how to use the mod, or want to give suggestions, you can go to github, or join our discord and ask questions there

If you are building a modpack

you might be interested in some of my other mods for modpacks:
AttributeSetter
RPGDamageOverhaul
FoodAttributes

Or Claims n Raids for servers!