Spend nucleotides on permanent upgrades in three sections: Core Genome, Signature Ability and Ultimate. Opens at level 2. The core upgrades and the two ultimate radius and charge upgrades are shared by every virus; the rest only count while your lineage is that virus. Each section has its own colour on its tab, its list and the upgrade panel: blue for Core Genome, orange for Signature Ability and pink for Ultimate.
Each upgrade has its base levels, then 10 bonus levels at a gentler rate, then two hidden mastery tiers of 10 levels each.
Mastery tiers stay hidden until you reach the top of what is shown Base-level prices multiply each level (×3.2 for 2–3 level upgrades, ×2.6 for 4, ×2.2 for 5–6, ×1.8 for 8, ×1.5 for 10) Bonus levels climb 25% per level; mastery levels 12% per level Hemorrhagic Fever, Furin Cleavage and Immune Escape have no extra levels From the Codex Permanent upgrades. The core ones are shared by every virus; ability and ultimate ones belong to one virus.
Fun fact: Pick an upgrade to see every level and milestone.
Petri Lab in the Codex Most upgrades unlock a special effect every 5 levels, with a major one every 10.
Hidden mastery milestones show as ??? until revealed Milestones apply automatically at the start of every run From the Codex Permanent upgrades. The core ones are shared by every virus; ability and ultimate ones belong to one virus.
Fun fact: Pick an upgrade to see every level and milestone.
Petri Lab in the Codex Advanced upgrades need 1 to 3 RNA strands to unlock, and every third level of any upgrade also costs RNA.
Levels 3 and 6: 1 RNA eachLevels 9, 12, 15: 2 RNA; levels 18, 21, 24: 3 RNALevels 27, 30, 33: 4 RNA; levels 36, 39: 5 RNAFully maxing a 40-level upgrade takes 39 RNA Unlocking every advanced upgrade takes 22 RNA From the Codex Ribonucleic acid: a single-stranded cousin of DNA that carries genetic messages and, in many viruses, the whole genome.
Fun fact: Some RNA molecules can act as enzymes (ribozymes), which hints that early life may have run on RNA alone.
RNA in the Codex +12 starting HP per level for 10 levels, then +6 HP per bonus level.
Max level 40; shared by every virus Level 1 costs 144 A; level 10 costs 5,536 A; 16,320 A for all base levels Lv 5 Self-Repair: regenerate 0.5 HP/sLv 10 Membrane Shield: block the first hit in every roomLv 15 Dense Coat: take 5% less damageLv 20 Living Fortress: block the first 2 hits in every room, +1 HP/sLv 25 and 35 Thick Capsid I and II: +4% max HP Lv 30 Last Stand (major): below 35% HP deal +50% damage and move 25% fasterLv 40 Bulwark (major): block 1 more hit per room and take 5% less damageFrom the Codex The protein shell that encloses a virus's genome, built from repeating subunits called capsomeres. Most are icosahedral (20 triangular faces) or helical.
Fun fact: Capsids self-assemble: the proteins snap together on their own, like a puzzle that builds itself.
Capsid in the Codex +8% damage per level for 10 levels, then +4% per bonus level.
Max level 40; shared by every virus Level 1 costs 144 T; level 10 costs 5,536 T; 16,320 T for all base levels Lv 5 Sharp Spikes: +5% critical hit chanceLv 10 Lysis Burst: cells you kill burst, damaging everything around themLv 15 Sharper Spikes: +5% critical hit chanceLv 20 Overwhelming Load: +1 projectile per shot (40% damage)Lv 25 and 35 Potent Load I and II: +3% damage Lv 30 Overkill (major): +1 projectile per shot (40% damage)Lv 40 Viral Snowball (major): each room cleared without a hit adds +5% damage (up to +50%); a hit loses a stackFrom the Codex Virulence is how much harm a pathogen causes; small mutations can make a strain far more aggressive.
Virulence in the Codex +5% move speed per level for 6 levels, then +2% per bonus level.
Max level 36; shared by every virus Like every speed bonus, it counts for 60% of its value, up to the organ's speed cap (1.5× base speed in the Nasal Passage, up to 3.6× in the Brain) Level 1 costs 120 C; level 6 costs 6,184 C; 11,238 C for all base levels Lv 5 Slipstream: dash recharges 15% fasterLv 10 Hit and Run: for 1.2s after every dash your shots deal double damageLv 15 Wide Uptake: pick up drops from 50% fartherLv 20 Phantom (major): untouchable 0.4s longer after each dash, dash recharges 15% fasterLv 25 and 35 Efficient Motion I and II: dash recharges 4% faster Lv 30 Afterburn (major): dashing bursts where you leave and leaves a damaging ringFrom the Codex +6% fire rate per level for 8 levels, then +2.5% per bonus level.
Max level 38; shared by every virus Level 1 costs 96 A + 96 T; level 8 costs 5,877 A + 5,877 T; 26,208 nucleotides for all base levels Lv 5 Fast Virions: shots fly 15% fasterLv 10 Piercing Stream: +1 pierce and shots fly 10% fasterLv 15 Recycled Parts: each kill heals 0.5 HPLv 20 Twin Stream (major): +1 projectile per shot (40% damage)Lv 25 and 35 Tuned Replication I and II: +2% fire rate Lv 30 Ricochet (major): shots pierce +2 cells and fly 15% fasterFrom the Codex +12% dash distance per level for 5 levels, then +4% per bonus level.
Max level 35; shared by every virus Level 1 costs 120 C + 72 A; level 5 costs 2,811 C + 1,687 A; 8,086 nucleotides for all base levels Lv 5 Quick Recovery: dash recharges 10% fasterLv 10 Ghost Dash: untouchable 0.3s longer after each dashLv 15 Slip Away: cells spot you from 10% closerLv 20 Hit and Run (major): double damage for 1.2s after every dashLv 25 and 35 Long Glide I and II: dash recharges 3% faster Lv 30 Shockwave (major): dashing bursts where you leave and leaves a damaging ringFrom the Codex A quick burst of movement.
Fun fact: Dash through attacks rather than away from them. Watch out for thymocytes, which copy your dash.
Dash in the Codex +20% ultimate radius per level for 3 levels, then +6% per bonus level. Named Pandemic Reach, Surge Reach, Hemorrhage Reach or Super-spreading Reach depending on the virus.
Max level 33; shared by every virus Level 1 costs 540 A + 360 T + 270 C; 16,895 nucleotides for all base levels Lv 5 Wider Wave: ultimate radius +15%Lv 10 Primed Outbreak: start every run with your ultimate chargedLv 15 and 25 Wider Wave I and II: radius +4% Lv 20 Global Outbreak (major): ultimate radius +40%Lv 30 Echo (major): ultimate charges 35% fasterFrom the Codex Each infected cell releases new virions that go on to infect its neighbours, so an infection can grow exponentially.
Fun fact: A single flu-infected cell can release thousands of new virions within hours.
Viral Spread in the Codex Ultimate charges 15% faster per level for 3 levels, then 5% per bonus level. Named Viral Shedding, Rapid Transcription, Viral Bloom or Aerosol Load depending on the virus.
Max level 33; shared by every virus Level 1 costs 450 T + 360 C + 225 G; 14,945 nucleotides for all base levels Lv 5 Steady Shedding: ultimate charges 10% fasterLv 10 Overflow: ultimate charges 30% faster and each kill heals 1 HPLv 15 and 25 Steady Shedding I and II: 4% faster Lv 20 Chain Outbreak (major): ultimate charges 40% fasterLv 30 Feast (major): every kill heals 2 HPFrom the Codex Shots mutate 0.4s sooner per level for 4 levels, then 0.1s per bonus level.
Max level 34 Level 1 costs 300 C + 150 G; 12,571 nucleotides for all base levels Lv 5 Restless Genome: shots mutate 0.5s soonerLv 10 Pre-Shifted: start every run with Antigenic Shift readyLv 15 and 25 Restless Genome I and II: 0.15s sooner Lv 20 Chaos Strain (major): +10% critical hit chanceLv 30 Primed Outbreak (major): start every run with your ultimate chargedFrom the Codex Small mutations that gradually change a virus's surface proteins so antibodies recognise it less well.
Fun fact: This is why the flu vaccine is updated almost every year.
Antigenic Drift in the Codex Antigenic Shift fires +4 bolts per level for 3 levels, then +2 per bonus level.
Max level 33 Level 1 costs 540 A + 360 C; 12,996 nucleotides for all base levels Lv 5 Quick Reassort: Antigenic Shift charges 15% fasterLv 10 Mass Reassortment: +12 boltsLv 15 and 25 Quick Reassort I and II: 5% faster Lv 20 Mass Reassortment II (major): +16 boltsLv 30 Endless Shift (major): Antigenic Shift charges 50% fasterFrom the Codex An abrupt, major change in a flu virus, caused when two strains infect the same cell and swap RNA segments (reassortment).
Fun fact: Shifts have produced new pandemic strains, including those of 1957, 1968 and 2009.
Antigenic Shift in the Codex Piercing shots pass through +1 more cell per level for 2 levels; bonus levels add +1 pierce every 3 levels.
Unlock: 1 RNA; max level 32Level 1 costs 900 T + 600 G; 6,300 nucleotides for both base levels Lv 5 Clean Cut: +1 pierceLv 10 Cleaving Strike: +15% damage and +1 pierceLv 15 and 25 Keen Edge I and II: +3% damage Lv 20 Executioner (major): +2 pierce and +10% critical hit chanceLv 30 Lysis Burst (major): cells you kill burst openFrom the Codex A flu enzyme that cuts the virus free from the host cell so new virions can spread.
Fun fact: Antiviral drugs like oseltamivir work by blocking it.
Neuraminidase (NA) in the Codex Infection lasts +2s and burns +3/s per level for 2 levels; bonus levels add +0.5s and +1/s.
Unlock: 2 RNA; max level 32Level 1 costs 900 A + 600 C + 480 G; 8,316 nucleotides for both base levels Lv 5 Hot Spell: infection burns +3/sLv 10 Hyperpyrexia: infection lasts +4s and burns 50% hotterLv 15 and 25 Hot Spell I and II: +1/s Lv 20 Wildfire (major): infection burns twice as hotLv 30 Contagion (major): cells you kill burst openFrom the Codex A raised body temperature triggered by the immune system. It slows some pathogens and speeds up immune responses.
Fun fact: The fever and aches of the flu come mostly from your own immune response, not directly from the virus.
Fever in the Codex Infected cells pass the infection on when they die; bonus levels make it burn +1/s.
Unlock: 3 RNA; max level 31Level 1 costs 2,250 A + 2,250 T + 1,800 C + 1,350 G Lv 5 Long Shedding: infection lasts +2sLv 10 Jackpot Strain: 1 in 6 nucleotide drops is a jackpot worth 4×Lv 15 and 25 Rich Pickings I and II: +3% nucleotides Lv 20 Outbreak Season (major): infection lasts +4sLv 30 Gold Rush (major): 1 in 4 nucleotide drops is a 4× jackpotFrom the Codex Each infected cell releases new virions that go on to infect its neighbours, so an infection can grow exponentially.
Fun fact: A single flu-infected cell can release thousands of new virions within hours.
Viral Spread in the Codex Store +1 more cell for Integration Surge per level for 3 levels; bonus levels add +1 stored cell every 3 levels.
Max level 33 Level 1 costs 450 A + 225 G; 9,747 nucleotides for all base levels Lv 5 Sticky Integrase: store +1 more cellLv 10 Loyal Hosts: allies fight +10s longerLv 15 and 25 Sticky Integrase I and II: allies fight +1s longer Lv 20 Mass Conversion (major): store +2 more cellsLv 30 Standing Army (major): allies fight +20s longerFrom the Codex A retroviral enzyme that copies RNA into DNA, the reverse of the usual flow of genetic information.
Fun fact: It's so error-prone that HIV mutates constantly, which is why it escapes the immune system and drugs.
Reverse Transcriptase in the Codex Latency lasts +1s per level for 3 levels, then +0.4s per bonus level.
Max level 33 Level 1 costs 450 C + 270 T; 10,397 nucleotides for all base levels Lv 5 Quiet Genome: Latency lasts +1.5sLv 10 Ghost Provirus: cells spot you from 15% closer and Detection rises 20% slowerLv 15 and 25 Quiet Genome I and II: +0.3s Lv 20 Invisible (major): Detection rises 40% slowerLv 30 Ambush Master (major): ambush hits deal double damageFrom the Codex A dormant state where a virus hides inside a cell without making new copies, invisible to the immune system.
Fun fact: Latent HIV reservoirs are the main reason the infection can't yet be cured.
Viral Latency in the Codex Allies fight +5s longer per level for 3 levels, then +2s per bonus level.
Unlock: 1 RNA; max level 33Level 1 costs 630 T + 360 G; 14,295 nucleotides for all base levels Lv 5 Deep Reservoir: allies fight +5s longerLv 10 Reservoir Tap: regenerate 1 HP per secondLv 15 and 25 Deep Reservoir I and II: +1.5s Lv 20 Blood Bank (major): elite kills heal 10 HPLv 30 Lifeline (major): regenerate 2 HP per secondFrom the Codex A fictional retrovirus inspired by HIV: it infects the immune system's own CD4 T cells and macrophages and slowly wears it down.
Fun fact: HIV copies its RNA genome into DNA and stitches it into the host's chromosomes, so infected cells carry it for life.
Retrovirus in the Codex Allies explode when their time runs out; bonus levels make allies fight +1.5s longer.
Unlock: 2 RNA; max level 31Level 1 costs 1,800 A + 1,350 T + 1,350 C + 900 G Lv 5 Fused Membrane: cells that touch you take 6 damageLv 10 Giant Cell: take 10% less damage and cells that touch you take 15Lv 15 and 25 Fused Membrane I and II: touching cells take 2 damage Lv 20 Spiked Fusion (major): touching cells take 25 damageLv 30 Rupture (major): cells you kill burst openFrom the Codex Integration Surge deals +50% damage to bosses per level for 2 levels, then +15% per bonus level.
Unlock: 2 RNA; max level 32Level 1 costs 900 A + 600 T + 480 G; 8,316 nucleotides for both base levels Lv 5 Cell Rupture: Surge deals +30 damage to bossesLv 10 Weakened Defenders: bosses have 10% less HPLv 15 and 25 Cell Rupture I and II: +10 boss damage Lv 20 Boss Breaker (major): bosses have 15% less HPLv 30 Overload (major): Surge deals +150 damage to bossesFrom the Codex The giant immune cell guarding the way to the next organ.
Fun fact: From the third organ on, every boss also has a signature skill on its own random clock, aimed at you.
Bosses in the Codex Integration Surge allies stay until the room is cleared; bonus levels make the ultimate charge 4% faster.
Unlock: 3 RNA; max level 31Level 1 costs 2,250 A + 2,250 T + 1,800 C + 1,350 G Lv 5 Dormant Copies: ultimate charges 10% fasterLv 10 Awakened Provirus: start every run with your ultimate chargedLv 15 and 25 Dormant Copies I and II: 3% faster Lv 20 Pre-Latent (major): start every run with Latency readyLv 30 Awakening (major): ultimate charges 40% fasterFrom the Codex Leftover DNA from ancient retroviruses that infected our ancestors and became a permanent part of the human genome.
Fun fact: Around 8% of human DNA comes from ERVs. Some of it even helps build the placenta.
Endogenous Retrovirus (ERV) in the Codex +5% bleed chance per level for 3 levels, then +1% per bonus level.
Max level 33 Level 1 costs 450 A + 225 G; 9,747 nucleotides for all base levels From the Codex A fictional filovirus inspired by Ebola: a long thread-like virion, often curled into a 'shepherd's crook'. Real filoviruses cause fever, bleeding and organ failure; some Ebola outbreaks have killed up to 90% of those infected.
Fun fact: Ebola was discovered in 1976 near the Ebola River in what is now the DR Congo. The 2014–16 West Africa epidemic infected over 28,000 people.
Filovirus in the Codex Bleeding deals +15% damage per level for 3 levels, then +4% per bonus level.
Max level 33 Level 1 costs 450 C + 270 T; 10,397 nucleotides for all base levels From the Codex Tiny cell fragments in the blood that clump together and plug wounds, forming clots with fibrin.
Fun fact: Platelets also help the immune system: they can trap bacteria and viruses and release antimicrobial proteins.
Platelets in the Codex Hemorrhage reaches +15% farther per level for 3 levels, then +4% per bonus level.
Unlock: 1 RNA; max level 33Level 1 costs 630 T + 360 G; 14,295 nucleotides for all base levels From the Codex The network of vessels carrying about 5 litres of blood around the body every minute, filled with red cells, platelets and immune cells.
Fun fact: Laid end to end, your blood vessels would stretch around 100,000 km, more than twice around the Earth.
Bloodstream in the Codex Bleeding deals +30% damage.
Unlock: 3 RNA; a single levelCosts 2,250 A + 2,250 T + 1,800 C + 1,350 G From the Codex A raised body temperature triggered by the immune system. It slows some pathogens and speeds up immune responses.
Fun fact: The fever and aches of the flu come mostly from your own immune response, not directly from the virus.
Fever in the Codex Spike volleys fire one shot sooner per level.
Unlock: 1 RNA; 2 levels onlyLevel 1 costs 600 A + 300 G; level 2 costs 1,920 A + 960 G From the Codex Surface glycoproteins such as flu's hemagglutinin, HIV's gp120 and the coronavirus spike (S) protein that bind a cell's receptors and drive fusion.
Fun fact: Spike proteins are the main target of most antiviral vaccines.
Spike Protein in the Codex Variant Surge lasts +1s per level for 3 levels, then +0.3s per bonus level.
Max level 33 Level 1 costs 450 C + 270 T; 10,397 nucleotides for all base levels From the Codex A fictional virus crowned with a halo of spike proteins that bind receptors on cells in the airways. It spreads before symptoms show, or with none at all.
Fun fact: Real viruses with a crown of spikes are called coronaviruses, from the Latin for crown; the 2003 SARS outbreak was caused by one.
Halovirus in the Codex Detection rises 5% slower per level for 3 levels, then 1% per bonus level.
Max level 33 Level 1 costs 630 T + 360 G; 14,295 nucleotides for all base levels From the Codex How aware the host's immune system is of you, from 0 to 100. It's the bar next to the eye at the top of the screen, and the more it fills, the harder the immune system fights back.
Fun fact: Stay out of fights for a few seconds and the bar drains on its own. Refuge rooms drop it fast.
Detection in the Codex Detection rises a further 15% slower.
Unlock: 3 RNA; a single levelCosts 2,250 A + 2,250 T + 1,800 C + 1,350 G From the Codex The slower, targeted immune response that learns the specific features of a pathogen and remembers them.
Fun fact: Vaccines work by training this system without the real disease.
Adaptive Immunity in the Codex 
