A game that grows with you
What Unlocks as You Level
New players aren't buried in systems on run one. Each mechanic unlocks for your whole save the first time any virus reaches its level, then it's introduced in your next run: a NEW MECHANIC UNLOCKED card that pauses the run the moment it first shows up, and (except the Cytokine Storm) a guarantee that it appears in that organ. Only one is introduced per run. The Cytokine Storm is the exception: it switches on from the fourth organ at any level. Trait milestones follow the same level, shared by every virus in your lineage.
Elemental power-ups and CRISPR start dropping from the first cells you kill in a fight.
Short bursts of elemental power, and the rare CRISPR.
Fun fact: Different power-ups run at the same time, and they follow you into the next room.
Power-ups in the Codex
Trade-off altars, receptor puzzles and event rooms (Siege, Mutagenic Pool, Lysis Chamber, Refuge) start appearing.
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
Cells can come in stronger tiers with affixes like Shielded, Swift or Vampiric, and drop better loot.
Stronger versions of normal cells, ringed in their tier colour.
Fun fact: Elites drop better loot, including gear.
Elite Cells & Affixes in the Codex
Dormant Virions can drop from tough enemies, each an extra life.
Ways to survive a killing blow.
Fun fact: The orange hourglass badge on your virus's portrait shows how many extra lives you have.
Extra Lives in the Codex
Filling Detection to 100 sends elite hunters that follow you from room to room.
The immune system's elite hunters (cytotoxic T cells), dispatched when Detection reaches 100.
Fun fact: When a pack is destroyed, Detection drops to 0 and stays frozen for 20 seconds: that's your breathing room.
Killer T Cells in the Codex
Most organs now grow a tumor that spreads over time and follows you if left alive.
Cancer growing in the host while you're there, and what happens if you leave it.
Fun fact: Kill tumors early: they only get worse, and they follow you if you don't.
Tumors & Metastasis in the Codex
Each organ's living hazards appear, along with abyss pits and drop shafts.
Parts of the tissue itself that can hurt you or help you.
Fun fact: Most hazards hurt cells as much as you: lure them in.
Hazards in the Codex
Other viruses competing for the host can appear after a fight.
Other viruses competing for the same host.
Fun fact: Rivals don't lock the doors, so running is always an option.
Rival Viruses in the Codex
At high Detection the host may take antivirals, a vaccine booster or interferon.
The host feeling sick and taking medicine when Detection is 75 or more.
Fun fact: Walking out of the room escapes a dose; surviving it pays out.
Treatments in the Codex
Rooms roll tiers with boons and drawbacks, outlined on the minimap.
Every room rolls a tier, from common to prismatic, with boons and drawbacks.
Fun fact: Check a room's border colour on the minimap before you walk in.
Room Tiers in the Codex
From the fourth organ on, a build that gets too strong fills the storm meter and draws adapted cells.
The immune system's answer to a runaway build: when you kill ordinary cells too easily, or barely get scratched, it starts sending cells built to resist you.
Fun fact: Kill the crimson ones first: they're the ones keeping the fight fair.
Cytokine Storm in the Codex
Lean on one shot type and cells start resisting it; the L level appears by the eye.
Adaptive immunity: the host studies how you attack and grows up as the infection goes on, so the same trick works less and less.
Fun fact: Mixing your shot types (or switching with Antigenic Shift) keeps it from ever pinning you down.
The Immune System Learns in the Codex
Each host now carries hidden traits, revealed when you infect it.
The person or animal you infect at the start of a run.
Fun fact: Rarer hosts have bigger effects and pay more nucleotides.
Hosts & Host Traits in the Codex
Burning, poison, chill and shock traits can be offered.
Pyrogens are molecules that trigger fever. Infections release them and the body heats up.
Pyrogenic Fever in the Codex
Skip ahead to any area you've already reached, with a 6-trait head start draft.
Beginning a run in an organ you've already reached.
Fun fact: Starting deeper is faster, but you miss the earlier organs' loot and traits.
Starting Deeper in the Codex
Bursting, chaining, bouncing, returning and orbiting shots.
Lytic viruses burst open their host cell, releasing a flood of new virions at once.
Lytic Burst in the Codex
Trait offers can roll purple tier.
Mutations you gain during a run.
Fun fact: Picking the same trait again stacks it.
Traits in the Codex
Stolen Membrane shields, Glycan Armor and the Incubation Period extra life.
Enveloped viruses wear a membrane stolen from the host, hiding behind 'self'.
Stolen Membrane in the CodexTrait offers can roll orange, red and Prismatic tiers.
Mutations you gain during a run.
Fun fact: Picking the same trait again stacks it.
Traits in the Codex
