Allumeria Biomes: All Four Plus the Two Sub-Biomes

The short answer

Four main biomes and two sub-biomes. The main four are Forest, Undergrowth, Snow and Desert. The two sub-biomes are Lush Forest and Autumnal Forest, both variants of the forest. On top of that, Early Access 0.15 added a separate 3D biome system, which is about atmosphere rather than terrain.

Forest — where you start

Trees, flint on the ground, hogs and fuzzies during the day, zombies and skeletons at night. The forest dungeon generates here, multiple times per world. 0.15 additions: a mossy variant of the rock monster, the crazed miner (“an old miner who lost their identity in the mines”) and the miner’s pickaxe, a boomerang-style weapon. Forest flowers now emit green particles.

The two sub-biomes are cosmetic-plus: Lush Forest and Autumnal Forest change tree and foliage colour — the red canopies in the official screenshots are autumnal forest.

Undergrowth — the layer under the forest

Not a surface biome but a full cave world with its own rules. Undergrowth Rock is a spawn surface for several monsters, Green Fuzzies live here, and the resources step up: iron, silver, gold, Allumerium Ore, diamonds, Heart Beets and the Flower of the Forest. Structures include abandoned huts and glowing mushroom shrines.

0.15 gave the Undergrowth its own 3D biome with fog and particle effects and reworked the lava layer at the bottom. The very bottom of the world is the Core, an unbreakable block.

Snow — the mid-game wall

Cold water and permafrost apply Freezing, which after patch 0.15.1 deals 30 damage every two seconds. Enemies: Snowman (40 HP), Snow Wizard (40 HP), Ice Fuzzy (25 damage), Yeti (30 damage, 40 HP) and the Iceflyer. Resources: cobalt ore, frost algae, pine trees (logs, planks, leaves, saplings, thick logs), ice cap mushrooms and orange fungi.

Two comfort items live here: hot springs, whose water heals you while you stand in it, and thermal vents, which convert water placed above them into spring water. The Snow Dungeon and the Snow Spirit are the biome’s gate.

Desert — the current end of the route

Palm trees (logs, leaves, saplings, planks), quicksand, surface lava pockets, giant skeletal remains structures, and palladium, the top ore tier. Enemies: tumbleweeds that roll along the surface, mummies, desert ghosts and a flying poison bulb. The desert dungeon tower and the Desert Worm close out Early Access content.

The 3D biome system

Introduced in 0.15 and easy to miss: 3D biomes are stored in 8×8×8 chunks and control atmosphere — fog density and colour, particle effects, sky colour, sunset colour — independently of the terrain biome. There are currently 3D biomes for Forest, Undergrowth, the Undergrowth lava layer, Snow, the Snow Dungeon and Desert. They are set at world generation for now, and the developer’s stated plan is to make them dynamic and player-changeable.

That is the honest answer to “how many biomes” as of 0.15.4: four terrain biomes, two forest sub-biomes, and six atmospheric 3D biomes that mostly overlap them.