Rust Biome

The Rust Biome is a map biome composed primarily of Rust rock and Mafic Rock that appears in several thermal variants (Base, Warm, Frozen). It is a resource-rich biome notable for large rust deposits and unique terrain features that make it a useful early- to mid-game source of materials and gases. The biome commonly contains solid rust, occasional deposits (Salt Deposit, Bleach Stone Deposit), and specialized features such as Ethanol Lakes and Sour Gas Rooms depending on the map variant.

Base variant climates are cool, with temperatures around -16.15 ↔ 6.85 °C. The Warm variant is hotter (Human Warm range 24.85 ↔ 39.85 °C) and introduces Sulfur and additional terrain features including Big Obsidian Rock, Bleach Stone Deposit, Salt Deposit and Sour Gas Room. The Frozen variant is cold (-46.15 ↔ -16.15 °C) and contains Snow but otherwise lacks special terrain features. Baseline generation places no liquids in the biome except where specific terrain features create them (for example, Ethanol Lakes produce Ethanol and Carbon Dioxide).

Rust rock and its terrain features interact with several game systems. Rust can be processed with a Rust Deoxidizer to produce Chlorine Gas and Salt; alternatively, melting rust is a more efficient method if the primary goal is to extract Gold. Bleach Stone Deposits create pockets of Chlorine Gas and Bleach Stone surrounded by Rust and Mafic Rock. Sour Gas Rooms combine Sour Gas and Salt Water and are typically surrounded by Sulfur, Rust and Mafic Rock. Ethanol Lakes produce Ethanol alongside Carbon Dioxide and are contained within Rust and Mafic Rock. Salt Deposits are also encountered, usually embedded in Mafic Rock.

Dasha Saltvines are exclusive plants to the Rust Biome and are an important tool for handling Chlorine output. A constantly running Rust Deoxidizer emits Chlorine; to neutralize that Chlorine using Dasha Saltvines requires exactly 5 Saltvines planted nearby. Domesticated Saltvines will recover about 36% of spent Salt, while wild Saltvines recover about 6%. Because Dasha Saltvines only spawn in this biome, a cluster without access to the Rust Biome cannot obtain them except via seed rewards from the Printing Pod; lacking Saltvines makes the GMO A-OK achievement unobtainable unless a seed is provided.

Practical notes and strategies:

• Rust is a dual-purpose resource: use Rust Deoxidizers to convert it into Chlorine Gas and Salt, or smelt/melt rust if you prioritize recovering Gold.
• Place Saltvines near planned Rust Deoxidizer locations if you intend to process rust on-site; five Saltvines are required to fully absorb chlorine output from one continuously operating Deoxidizer.
• In Warm variants, expect Sulfur and additional hazardous pockets (Sour Gas Rooms, Bleach Stone Deposits); plan gas routing and insulation accordingly.
• Bleach Stone pockets create localized Chlorine Gas hazards but also provide Bleach Stone as a resource; isolate or ventilate these rooms before harvesting.
• Ethanol Lakes in the biome are sources of Ethanol and Carbon Dioxide but are limited to specific terrain features rather than general rust fields.
• The temperature of the biome affects base heat management: Warm maps may require cooling, Frozen maps reduce thermal management concerns but limit plant/critters.
• Because many gases in the Rust Biome are heavier than Oxygen, they tend to sink below oxygenated areas; use gravity and airflow controls to simplify containment and venting.

The Rust Biome is therefore a flexible but occasionally hazardous region that supplies salt, Chlorine Gas, and rust-derived metals while offering unique plant life (Dasha Saltvines) that enable localized chemical recycling through domestication and careful base planning.