Milestones count from the deepest organ your whole lineage has reached in Infect Game Mode, whichever virus got there. They switch on mid-run the moment you first arrive.
- A banner announces when your virus adapts
- Only Infect Game Mode unlocks new milestones
- Influenza A has no milestones

Retrovirus: Lymph Node
Ally boostReaching the Lymph Node makes Retrovirus's captured cells hit harder and take more punishment, so your released allies stay useful in every organ and game mode.
- Allies deal more damage
- Allies hold up longer in fights

Retrovirus: Gut
Kamikaze unlockAt the Gut, captured cells get a little stronger and tougher, and every cell your shots kill starts adding a kamikaze to a store that bursts out when full.
- Unlocks the kamikaze store
- A small boost to ally damage and toughness

Retrovirus: Liver
Big boostThe Liver is a big step up for Retrovirus. Captured cells become much stronger and tougher, and both Latency and Integration Surge hit far harder.
- A major jump in ally damage and toughness
- Latency pulses and Surge blasts hit much harder

Retrovirus: Brain
Final adaptationReaching the Brain pushes everything further. Captured cells grow far stronger and tougher again, and Latency and Integration Surge hit harder still, stacking with the Liver bonus.
- Allies become massively stronger and tougher
- Stacks with the Liver bonus for huge Surges
- All Retrovirus milestones combine into a fearsome ally army

Filovirus: Lungs
Ability boostFilovirus adapts early. Once your lineage reaches the Lungs, its bleeds, Hemorrhage and Viral Hemorrhage all hit much harder, in every organ and game mode.
- Every Filovirus ability hits much harder
- Arrives early in the host

Filovirus: Bloodstream
Ability boostIn the Bloodstream, bleeds, Hemorrhage and Viral Hemorrhage grow stronger again, and every cell you have bleeding now deals less damage, not just the ones Hemorrhage hit.
- Stacks on top of the Lungs bonus
- Any bleeding cell is weakened

Filovirus: Gut
Bleed boostAt the Gut, all bleeding gets a little stronger, and cells caught by Hemorrhage are weakened even further, so crowds hurt you less.
- Bleeds get a small damage boost
- Hemorrhage weakens cells a bit more

Halovirus: Lymph Node
Ability boostHalovirus's first big adaptation arrives at the Lymph Node. From then on, its infection, spike volleys, outbreaks and ultimate all hit much harder, in every organ.
- Every Halovirus ability hits much harder
- Applies in every organ and game mode

Halovirus: Gut
Volley boostAt the Gut, Halovirus sharpens its kit. Spike volleys deal a bit more damage, and the Fury surge pushes your damage even higher than before.
- Spike volleys hit a little harder
- The Fury surge gets stronger

Halovirus: Bone Marrow
Ability boostDeep in the Bone Marrow, Halovirus adapts again. Infection, spike volleys, outbreaks and the ultimate all hit much harder, stacking with the Lymph Node bonus.
- Another big boost to every ability
- Multiplies with earlier milestones

Halovirus: Brain
Final adaptationThe Brain brings Halovirus's biggest adaptation. Infection, spike volleys, outbreaks and the ultimate hit harder than ever, combining with the earlier milestones into a huge total boost.
- The strongest single Halovirus milestone
- Combines with the Lymph Node and Bone Marrow bonuses