Pathogenic biomes are the six main progression regions (Skin, Intestine, Stomach, Liver, Lungs, Heart) plus a secret Brain level that opens after the Heart boss, per TechTimes launch coverage and the Slug Disco game-info page. Each biome has an environmental mechanic — stomach acid, lung airflow, heart currents — and at least one boss. Boss names are limited to what the cited gameplay tips articles attribute; clearing a biome boss awards a plasmid-tree unlock.
The six main Pathogenic biomes plus the secret Brain level
The Pathogenic biome list as of 2026-08-05 has six main progression regions and one secret biome. The TechTimes launch coverage records the same six main regions and confirms the secret Brain level; the pathogenicgame.com overview and the Slug Disco game-info page both describe the lung, heart, and brain regions by name.
The six main Pathogenic biomes plus the secret Brain level
Skin biome
The Skin biome is the first progression region. The Slug Disco game-info page frames the Skin biome as the tutorial-by-immersion region: combat rooms are short, the immune-cell density is low, and the room loop reads as the four-room structure from the very first room. The 10 Tips and Tricks video uses the Skin biome to teach the editor habit, because the cost of a wrong pick is recoverable.
Intestine biome
The Intestine biome is the second progression region and the first biome where the room loop tests a build. The 10 Advanced Tips video frames the Intestine biome as the biome where room-clearing discipline starts to pay off, because the immune-cell density rises a step.
Stomach biome
The Stomach biome is the third progression region and the first biome with a named environmental mechanic. The TechTimes launch coverage and the pathogenicgame.com overview both name stomach acid as the biome's environmental mechanic; the room loop now requires the build to manage acid pools as well as immune cells.
Liver biome
The Liver biome is the fourth progression region and the biome where the build's contact options are tested most harshly. The Slug Disco game-info page frames the Liver biome as a contact-biome: the immune-cell density is high enough that ranged builds have to commit to a connected network or fall behind.
Lungs biome
The Lungs biome is the fifth progression region. The pathogenicgame.com overview names the Lungs biome as one of the three biome stages that test a build most harshly, and the Slug Disco game-info page pairs the Lungs biome with airflow as the environmental mechanic.
Heart biome
The Heart biome is the sixth main progression region. The pathogenicgame.com overview names the Heart biome as the second of the three biome stages that test a build most harshly, and the Slug Disco game-info page pairs the Heart biome with currents as the environmental mechanic.
Secret Brain biome
The Brain biome is the secret seventh biome that sits at the end of the run. The TechTimes launch coverage records the secret Brain level; the pathogenicgame.com overview names it as "the complex neural network of the brain" and frames it as the final test of a build. It opens after the Heart biome's boss is cleared.
Environmental mechanics by biome
The Pathogenic biome environmental mechanics are the named mechanics that change the room loop beyond immune-cell density. The TechTimes launch coverage, the pathogenicgame.com overview, and the Slug Disco game-info page are the sources for the mechanic list below.
Environmental mechanics by biome
Stomach acid
Stomach acid is the Stomach biome's environmental mechanic. Acid pools sit on the room floor and damage the parasite on contact; the room-clearing discipline from the Skin and Intestine biomes has to keep the parasite out of the acid while still clearing the immune cells.
Airflow in the Lungs
Airflow is the Lungs biome's environmental mechanic. Airflow pushes the parasite and the immune cells in the same direction; a build with a knockback mutation or a Spike-led contact archetype uses the airflow to keep the immune cells at a distance.
Currents in the Heart
Currents are the Heart biome's environmental mechanic. Currents are stronger than airflow and pull the parasite toward the boss arena faster than the room loop rewards; the Slug Disco game-info page frames the Heart currents as the test that distinguishes a build that can hold a role under pressure from one that relied on a single offensive mutation.
Boss per Pathogenic biome
The Pathogenic biome boss framing is recorded by the cited gameplay tips articles. Boss names are limited to what the cited sources explicitly attribute; this page does not invent a boss roster beyond what those sources record.
Boss per Pathogenic biome
Biome bosses the cited sources name
The idreamofindie Pathogenic review and the 10 Tips and Tricks video frame each biome as having at least one boss. The 10 Advanced Tips video credits the boss count as the launch build's headline progression checkpoint: six main bosses, one per main biome, with the secret Brain biome adding a seventh encounter.
The first boss as a survival check
The idreamofindie Pathogenic review treats the first biome boss as a survival check, not a damage race. The 10 Tips and Tricks video reinforces the same framing: do not commit to a full damage rotation before the boss's first phase ends, save one mutation for the boss's last quarter. The Pathogenic beginner guide is the right entry point for first-boss advice.
Boss name scope
This page does not list every Pathogenic biome boss by name because the launch sources name the biomes by region without enumerating a per-biome boss name. Boss names beyond what the cited sources attribute are not announced as of 2026-08-05.
How Pathogenic biomes hand off to the plasmid tree
The biome-to-plasmid-tree handoff is the moment a run converts its in-run progress into permanent progress. Clearing a biome's boss awards a plasmid unlock that lands on the parasite's per-parasite tree.
How Pathogenic biomes hand off to the plasmid tree
Per-biome plasmid unlocks
Each cleared biome's boss awards a plasmid unlock. The 10 Evolution Secrets video frames the unlock cadence as the reason a player who commits to one parasite sees the tree branch by biome, not by organelle category. Spreading runs across multiple parasites slows every tree down.
Biome-to-build handoff as the deeper signal
The idreamofindie Pathogenic review frames the biome-to-build handoff as the single biggest differentiator between a run that reaches the Heart boss and a run that ends early. A build that read the Stomach biome's acid pools correctly and drafted a defensive mutation in the Liver biome is the build that reaches the Heart currents and survives them. The Pathogenic builds page is the right next page for the per-archetype reading.
Sources
Sources checked 2026-08-05.
FAQ
How many biomes are in Pathogenic?
Pathogenic biomes as of 2026-08-05 include six main progression regions (Skin, Intestine, Stomach, Liver, Lungs, Heart) plus a secret Brain level that opens after the Heart biome boss is cleared. The TechTimes launch coverage records the same six main progression regions and confirms the secret Brain level.
How many bosses are in Pathogenic?
The cited sources record at least one boss per biome. The Pathogenic biome list as of 2026-08-05 has six main bosses (one per main biome) plus the encounter in the secret Brain biome. A full per-biome boss name roster beyond what the gameplay tips articles attribute is not announced as of 2026-08-05.
What is the secret Brain biome?
The Brain biome is the secret seventh biome that opens after the Heart biome's boss is cleared. The TechTimes launch coverage records the secret Brain level, and the pathogenicgame.com overview frames it as "the complex neural network of the brain." It is not announced as part of the six main progression regions; it is the reward biome.
What are the environmental mechanics by biome?
The cited sources name three biome environmental mechanics: stomach acid (Stomach biome), airflow (Lungs biome), and currents (Heart biome). The Skin, Intestine, and Liver biomes are not assigned a named environmental mechanic by the launch sources, though the room loop in those biomes still changes with immune-cell density.
How do biomes hand off to the plasmid tree?
Each cleared biome's boss awards a plasmid unlock, and that unlock lands on the parasite's per-parasite tree. The 10 Evolution Secrets video frames the cadence as the reason a player who commits to one parasite sees the tree branch by biome. The Pathogenic builds page is the right next page for the per-archetype reading.