Genesis: Atlas

🏔️ Version 1.3 (2026-09-30) — The Mountain Update

• Target Platform: Minecraft 26.1 · NeoForge 26.1.0.19-beta+ · Java 25 · Requires Genesis: Core 1.0.0+ · Pairs with Genesis: Horizon 1.0.0+
• Summary: Mountains are no longer drawn with noise. Ranges now rise, and the rivers draining them carve their valleys. Valleys, ridges and rivers all come from the same drainage network, and the ground is painted by its slope: grass fades into scree and bare rock, every range has its own rock, and snow lies only where it can hold.
• ⚠️ New world required: Terrain is generated differently from 1.2. Chunks already generated in an old world keep their old shape, so there will be hard seams where old and new chunks meet.
• ⛰️ Erosion-Carved Mountain Ranges:
  • Long, broad, separate ranges replace the scattered mountains of earlier versions. Mountains cover about a sixth of the land; wide plains and valleys fill the rest.
  • Every range is worn down by its own streams (a stream-power erosion model on the drainage grid): dendritic valleys branch from the crests to the mountain foot, with rounded ridges and broad pyramidal peaks between them.
  • Valley floors widen downstream, alternating between narrow gorges and wide basins. Branching gullies are scored down the slopes, and their lines stay continuous over the crests.
  • Summits reach roughly Y 250–290.
• 🏞️ Rivers That Follow Their Valleys:
  • Mountain brooks and rivers run down the valley floors the erosion carved, and every one rises from a visible spring pool.
  • River water stays within its banks through mountain valleys and joins the plains' rivers without climbing or breaking at region borders.
• 🎨 Realistic Mountain Painting:
  • Soft grass-to-rock transition: grass thins out with the slope through patches of coarse dirt and gravel into cobble and bare rock, with no hard line. Gullies carry gravel streaks down the mountainside.
  • Every range has its own rock: some ranges are dark (tuff and stone), some grey (stone and andesite), some pale as limestone (diorite, with calcite on the highest faces). Rock pales towards the summits, and no black basalt or deepslate streaks run down mountain faces.
  • Snow where it holds: snow starts as thin layers just below the snow line and thickens higher up. It collects in gullies and couloirs, stays thin on windswept ribs, and slides off steep faces, so bare rock shows through instead of an all-white cap. North faces hold snow lower than south faces.
  • Vanilla's frost no longer dusts bare rock faces with snow when chunks are generated. Snow that falls later in the game still settles as usual.
• 🌲 Bigger Climates & Mountain Biomes:
  • Climate belts and biomes are about 1.6× larger, so each region keeps its character for thousands of blocks.
  • Valley floors inside a range keep their climate's own lowland biomes. Montane spruce forest is limited to a belt below the treeline, then krummholz, alpine meadow and bare rock.
• 🗺️ Coasts & Strategic Sites:
  • Larger continents with steeper nearshore shelves, so sheltered harbour coves appear again.
  • Mountain passes and harbours are no longer reserved twice where a site straddles two survey cells.
• 🧹 Retired: The erosion engine replaces the old ridged-noise mountains and their U-shaped glacial valleys. Glacial mountain tarns are temporarily retired and will return in natural mountain basins.
• 🧪 Validation: 212 passing automated unit tests, GameTests and in-game playtesting.