The Last Leukocyte

You are one white blood cell in a body under attack. Viruses, bacteria, fungi and parasites pour in from every side, more every minute. Your cell fights on its own: you steer. Collect the antigen that destroyed germs leave behind to level up, then pick new weapons and traits so they combine into a build. Last fifteen minutes and the organ's boss comes for you.

How to play

• Move with WASD or the arrow keys, by holding the left mouse button (your cell moves toward the pointer), by dragging anywhere on a touch screen, or with a gamepad's left stick.
• Weapons fire by themselves. Keep moving, keep germs off your cell, and sweep up the glowing antigen.
• Level up: pick one of three cards with the mouse, a tap, or the keys 1 to 4. Reroll the cards with R, skip with X (you heal a little), or banish a card you never want again with B.
• Maturation: a weapon at level 6 matures into a stronger form when you also carry its partner trait. The Weapons page of the Codex names each weapon's partner.
• Elites and mutants drop booster capsules holding one, three or five free upgrades. Mutants run, so catch them.
• ATP from every run buys permanent Immune Memory upgrades. Beat an organ's boss to unlock the next organ and a harder Fever level, up to Fever 10.
• The daily challenge gives everyone the same cell, organ and twist for the day. Survive ten minutes to keep your streak.
• Pause with P or Esc; M turns the sound on or off.

The biology

The cells, germs and weapons are based on the real immune system: neutrophils cast DNA nets, NK cells punch holes with perforin, and B cells tag germs with antibodies. The Codex has a short fact for each one. Numbers and behaviour are simplified for play.