Know your enemy
The Immune System
Real immune cells, each with a job that becomes a fighting style. Get noticed and the host escalates: hunter squads, treatments, Killer T cells, elite cells with affixes, and an adaptive immune system that learns how you play.
Immune cells
Real cells with real jobs
Every fight is full of first responders, and each one hunts in its own way, based on what the real cell does. Neutrophils swarm, Macrophages charge down a marked line, B cells slow you and Dendritic Cells never attack but keep alerting the whole room until you kill them. From the Lymph Node on, deep organ specialists join them with stranger tricks.
At a glance
- Monocyte: flees until it's cornered, then turns to fight
- Memory B Cell: fires the moment it spots you and remembers your last shot type
- Eosinophil: leaves acid pools that burn other cells too
- Thymocyte: drifts in packs and dashes at you every time you dash
- Myeloblast: rushes straight at you and bursts into neutrophils when it dies
Detection
Stay hidden or get hunted
Cells start unaware, each watching with a sight cone, so sneaking up on them lets you ambush. Fighting fills the eye meter from green to yellow to pulsing red, and each threshold escalates the response with hunter squads, treatments and finally Killer T cells. Go quiet and it cools down again.
- Each hunter squad is bigger than the last and comes from a far door
- Kills of unaware cells raise Detection less, and cells the immune system sends never raise it
- The Refuge, puzzle rooms, Latency and wiping out a Killer T pack all lower Detection
- Immune Alert makes everything tougher the longer a run lasts, so keep moving
- Fights come in waves, and the reinforcements arrive already hunting
Killer T cells
The hunters that follow you
Max out Detection from the Lungs on and Killer T cells come for you, following through every door and keeping their wounds. Each one splits into a pair of smaller copies when it dies, only the originals drop loot, and the pack always moves a little faster than you, so you can't simply outrun it. Destroy the whole pack and Detection empties and freezes for a while, but the next generation comes back stronger with a new skill.
- The Refuge won't hide you from Killer T cells
- Only the next organ or a drop shaft makes them lose your trail
- Later generations add perforin rings, homing granzymes and packs of three
- Every pack you wipe out raises the Immune System Level
- Killer T cells unlock as your skill tree grows
Treatments
The host fights back with medicine
When Detection runs high the host may take a dose, announced by a warning pulse, though never in a boss room. Antivirals make you fire slower, Boosters make cells take less damage and Interferon makes you take more. Survive the dose for a reward, or leave the room to escape it and give the reward up.
At a glance
- Capsules and vials hide behind crowds but are frail on their own
- Every dose is stronger than the last
- The medicine changes with the virus you play
- Radiation Therapy can follow a metastasis
Elites and affixes
Seven tiers of trouble
Any cell can roll an elite tier when it spawns, from white up to prismatic, coloured like gear. Elites are bigger and tougher and drop much better loot, and they show up more often in deeper organs and at higher Immune Alert. From Rare up they also carry affixes, named over their heads.
- Affixes include Swift, Armored, Shielded, Regenerating, Vampiric, Volatile, Splitting and Enraged
- Mythic and Prismatic elites always drop gear
- Explosive shots crack armour, and electric shots tear through shields
- Even bosses can roll an elite tier
Adaptive immunity
A host that learns how you play
The Immune System Level rises with every organ and every Killer T generation, and it sets how hard treatments hit. The immune system also learns your most-used shot type and starts to resist it. Get too far ahead of the host and the Cytokine Storm meter fills, sending crimson adapted cells that are tougher, faster and pierce your defences.
At a glance
- Influenza A's drifting shot types help it dodge resistance
- Shot type resistance is switched off in Endless Game Mode
- Storm Surge keeps escalating for as long as the meter stays full
- Helper T cells and Basophils buff nearby cells, which glow blue
- The Cytokine Storm starts at the Lymph Node and only wakes up once your build has several traits