Mineclonia Wiki » Guides » MC mapgen

By: Mikita Wiśniewski

3 Apr 2026

MC mapgen

Mineclonia Minecraft mapgen (simply called Lua mapgen or custom mapgen) refers to halon’s mcl_levelgen map generator, which replicates Minecraft 1.18+ world generation almost perfectly, including terrain, caves, biomes, and other uncopyrightable features[1]. It’s implemented as a mod in Lua (with optional FFI code in C) that replaces the otherwise empty singlenode mapgen; this means that the system requirements to generate worlds using MC mapgen are higher than for default mapgens (v7, valleys, etc).

To play with MC mapgen in singleplayer, you should:

1. Make sure the Custom singlenode map generator toggle is set to ON;

2. Create a new world and select the singlenode mapgen during world creation.

Differences

Coordinate system

Minecraft’s coordinate system is right-handed (Z+ is South, Z- is North), while Luanti’s coordinate system is left-handed (Z+ is North, Z- is South). This means that the Z coordinate in MC mapgen worlds has its sign flipped compared to Minecraft, or in other words the world generation is mirrored across the Z axis.

In addition to the Z flip, the Y coordinate is shifted down by 64 nodes (blocks) to make the water level (which is at Y=64 in Minecraft) match Luanti’s default water level (which is at Y=0).

See Coordinate converter tool for a convenient way to convert exact Minecraft coordinates to exact mcl_levelgen coordinates.

Seeds

Minecraft’s world seeds are represented by 64-bit signed integers (ranging from −2⁶³ up to 2⁶³−1), while Luanti’s mapgen seeds are represented by 64-bit unsigned integers (ranging from 0 up to 2⁶⁴-1). Both allow ~18.4 quintillion possible seed variations, just represented differently (Minecraft’s numerical seeds can go into the negatives, but Luanti’s cannot), so they must be converted first.

See Seed converter tool for a convenient way to convert Minecraft seeds (numerical and alphanumeric) to exact mcl_levelgen seeds.

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[1]

Naturally generated structures (trees, dungeons, villages, etc.) weren’t replicated one-to-one, and their placement differs; their design is the same as with any other Mineclonia mapgen. The specific combination of Perlin and Simplex noise functions, as well as miscellaneous other algorithms for additional world generation features, is not protected by copyright. The mcl_levelgen code is written in Lua for the Luanti engine, whereas Minecraft’s implementation exists in Java and C++. halon states that he followed a standard reverse-engineering approach based on publicly available community documentation and targeted unit test compliance. No Mojang code was used.