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Not every room is a fight

Special Rooms

Special rooms play by their own rules and are outlined in colour on the minimap. The Mutation Chamber and Gene Chamber are in every organ; altars, puzzles and event rooms arrive with the Special Rooms mechanic (Level 3), and tumor rooms with Tumors & Metastasis (Level 7). Trade-off Altars, puzzle rooms, Gene Chambers, Immune Sieges and Lysis Chambers have their corners cut into an octagon 40% of the time; the Mutation Chamber, Mutagenic Pool, Refuge and tumor rooms are always plain rectangles.

A tumor room: the Filovirus fights a Colon Carcinoma in the Gut
A tumor room: the Filovirus fights a Colon Carcinoma in the Gut
On this page12
  1. Mutation Chamber
  2. Gene Chamber
  3. Receptor Puzzle
  4. Signal Puzzle
  5. Puzzle Reward
  6. Trade-off Altars
  7. Immune Siege
  8. Mutagenic Pool
  9. Lysis Chamber
  10. Refuge
  11. Event Room Frequency
  12. Tumor Room

Mutation Chamber

Every organ

An upgrade room where a loose strand of DNA drifts: a free mutation orb, a vesicle chest and a few nucleotides.

  • One per organ, at a dead end
  • Touch the orb to choose 1 of 3 traits
  • Also drops 8 nucleotides
  • Its sign reads UPGRADE CHAMBER
From the Codex

Viruses mutate constantly as they copy themselves. Most mutations are harmful, but a few give an advantage and spread through the population.

Fun fact: RNA viruses like flu make roughly one copying error per genome they replicate.

Mutation Chamber in the Codex

Gene Chamber

Every organ

A key guardian holds this organ's gene; beat it, then take the gene to open the sealed door.

  • Usually tucked in a dead end
  • The gene appears where the guardian stood
  • The gene also grants a lasting passive bonus for the run
From the Codex

Viruses carry genes for tools that break host barriers, like neuraminidase that cuts through mucus, or fusion peptides that merge viral and cell membranes.

Fun fact: Neuraminidase is the target of Tamiflu: block it, and new flu virions get stuck to the cell they came from.

Gene Cassette in the Codex

Bind all the receptors at once: light every pad before the first one fades.

  • 3–4 pads on a ring around the room
  • Each pad stays lit 4.5 s after you step off
  • At most one puzzle per organ (45% of organs)
From the Codex

Viruses enter cells by binding receptors: proteins on the cell surface. Flu binds sialic acid; HIV needs CD4 plus a co-receptor (CCR5 or CXCR4), engaged in the right sequence.

Fun fact: Some people carry a CCR5 mutation (Δ32) that makes them highly resistant to most HIV strains.

Receptor Puzzle in the Codex

Repeat the signal: watch 4 pads flash in order, then step on them in the same order.

  • A wrong pad shows WRONG SIGNAL, raises Detection and replays the signal
  • Shares the one-puzzle-per-organ slot with the Receptor Puzzle
From the Codex

Viruses enter cells by binding receptors: proteins on the cell surface. Flu binds sialic acid; HIV needs CD4 plus a co-receptor (CCR5 or CXCR4), engaged in the right sequence.

Fun fact: Some people carry a CCR5 mutation (Δ32) that makes them highly resistant to most HIV strains.

Receptor Puzzle in the Codex

Solving either puzzle releases a strand of DNA and a pile of loot.

  • A mutation orb, a vesicle chest, 10 nucleotides and 2 Chaperone Proteins
  • Detection drops by 10
  • In Pandemic Game Mode, a chance of an RNA Strand
From the Codex

Viruses enter cells by binding receptors: proteins on the cell surface. Flu binds sialic acid; HIV needs CD4 plus a co-receptor (CCR5 or CXCR4), engaged in the right sequence.

Fun fact: Some people carry a CCR5 mutation (Δ32) that makes them highly resistant to most HIV strains.

Receptor Puzzle in the Codex

Trade-off Altars

Choice room

A crossroads of 2–3 altars, each a bargain: something strong for a price. Step onto one, or walk away.

  • Offers are drawn from 5 bargains
  • Only one can be taken
  • Appears in about 60% of organs, and always in the organ that introduces special rooms
From the Codex

Evolution is full of trade-offs. A mutation that makes a virus more aggressive can also make it easier for the immune system to spot, or less stable outside the body.

Fun fact: Viruses that kill their hosts too quickly often spread worse; many evolve to become milder over time.

Trade-off Altars in the Codex

Immune Siege

Event room

The doors seal and reinforcements keep pouring in; survive the timer for a reward.

  • Lasts 22 seconds
  • A fresh squad arrives every 4.5 s: 3 cells in the Nasal Passage, one more per organ deeper
  • Nothing its squads do raises Detection; in Pandemic Game Mode they're the organ's own cells, as many and as tough as your deepest organ's squads
  • Squads are neutrophils, B cells and macrophages (platelets, NK cells and neutrophils in the Bloodstream)
  • Survive and the room's cells retreat, leaving a vesicle chest and a mutation orb
  • Being knocked out fails the room, not the run: you recover to the health you came in with
From the Codex

When an infection is detected, the immune system recruits waves of white blood cells to the site, guided by chemical signals called chemokines.

Fun fact: Inflammation (redness, swelling, heat) is largely caused by immune cells flooding into infected tissue.

Immune Siege in the Codex

Mutagenic Pool

Event room

Bathe in the pool for a random trait, often a rare one, at a price.

  • Costs 20% of your current HP (it can't kill you)
  • The trait's tier odds are boosted: never Common
  • One use
From the Codex

Mutagens like radiation and some chemicals raise mutation rates. Some antivirals, like molnupiravir, work by pushing viruses into so many mutations they collapse.

Fun fact: This is called 'error catastrophe': too many mutations and the virus can no longer make working copies.

Mutagenic Pool in the Codex

Lysis Chamber

Event room

The doors seal around 9 host cells: burst as many as you can in 18 seconds.

  • Every host cell drops nucleotides
  • Burst them all for a vesicle chest and a mutation orb
  • If time runs out, the rest escape
  • Being knocked out fails the room, not the run
From the Codex

A virus can't copy itself on its own. It hijacks a host cell's machinery to make new virions, and lytic viruses then burst the cell open to release them.

Fun fact: One infected cell can release thousands of new flu virions before it dies.

Lysis Chamber in the Codex

Refuge

Event room

A quiet host cell: slip inside to heal and lose the immune system.

  • Heals 50% of max HP
  • Detection drops by 30
  • Hunting cells lose track of you (bosses and Killer T cells don't)
  • One use
From the Codex

Some viruses hide inside cells without making new copies (latency). HIV hides in resting immune cells as a 'reservoir' that drugs can't reach.

Fun fact: Herpes viruses go latent in nerve cells for life; that's why cold sores come back.

Refuge in the Codex

Each organ holds two or three different event rooms, picked from Immune Siege, Mutagenic Pool, Lysis Chamber and Refuge.

  • Each kind appears at most once per organ
  • Event rooms and altars are hidden until the Special Rooms mechanic unlocks at Level 3
From the Codex

Rooms that aren't straight fights, outlined in colour on the minimap.

Fun fact: Refuges are worth remembering: you can come back to one when Detection gets high.

Special Rooms in the Codex

Tumor Room

Level 7 unlock

A cancer grows here, a different one in every organ; destroy it for a huge payout before it spreads.

  • Grows in about 70% of organs once Tumors & Metastasis is introduced
  • The doors never lock: you can back out, but it keeps growing and spreading while you're away
  • The HUD tracks its stage and spread
  • Left alive, it follows you into the next organ
From the Codex

Cancer is the host's own cells dividing out of control after mutations break their brakes. Some viruses (HPV, Epstein-Barr, hepatitis B) can help cause it.

Fun fact: Oncolytic viruses are engineered to infect and burst cancer cells; T-VEC, a modified herpes virus, is approved for melanoma.

Tumor Room in the Codex

See also