A respiratory pathogen enters the airway. You have 14 days and four energy a day to clear it — coordinating innate defence, helper T-cells, antibodies and cytotoxic T-cells across six regions of the body, while your own inflammation threatens the organs you're defending. Free in the browser, no install and no account.
Antibodies cannot reach a pathogen hiding inside a cell. That single constraint is the whole game. Win it and you will have used the difference between humoral and cell-mediated immunity, not just read the definitions.
INNATE RESPONSE — macrophages, neutrophils and complement respond within minutes against anything, but the response is non-specific and the inflammation it triggers damages host tissue.
PRIME LYMPH NODE — dendritic cells carry antigen to the lymph node and present it to helper T-cells (CD4+). This activation takes days, and it is the gate: nothing adaptive unlocks until it completes. Priming late is the most common way to lose.
ANTIBODIES — B-cells secrete antibodies that neutralise free pathogen and tag it for destruction, leaving memory B-cells behind. They do nothing about infected cells.
CYTOTOXIC T-CELLS — CD8+ cells recognise infected cells by the antigen on their surface and kill them. This is the only way to clear an intracellular infection, and killing your own cells causes local damage.
FEVER / CYTOKINES — slows pathogens everywhere, but an over-strong systemic response is a cytokine storm. Immunopathology can harm organs more than the pathogen does.
ANTI-INFLAMMATORY — regulatory T-cells dampen the response to protect tissue, but suppressing immunity lets the pathogen rebound. Balancing those two is why severe infections are genuinely hard to treat.
VACCINATE — presents antigen without disease, establishing memory in advance so the response is fast from day one — until antigenic drift erodes the match.
As it replicates it accumulates mutations. A drifted strain is less recognised by existing antibodies and memory — which is the reason flu vaccines are reformulated every year. The drift here is deterministic, so a class can replay the same scenario and compare strategies fairly.
One playthrough runs about fifteen minutes. It needs no login, no install and no student accounts — a link is enough. Win and loss screens both debrief the lesson, and the field log surfaces the underlying immunology fact behind every move, so students who lose still leave with the concept. Suitable for senior biology (Grades 10–12) covering innate and adaptive immunity, vaccination, and immunological memory.