Sea Hero Quest is a mobile and VR game developed by the studio Glitchers in partnership with Deutsche Telekom, Alzheimer's Research UK, University College London, and the University of East Anglia. The player navigates a small boat through mazelike waterways, collecting checkpoints and firing flares to indicate remembered positions. The mechanics are deceptively simple; what lies beneath them is one of the most ambitious citizen-science instruments ever designed. Each play session generates granular spatial navigation data — the cognitive ability that deteriorates earliest and most reliably in the progression of Alzheimer's disease. Over 4.3 million players worldwide have contributed sessions, generating data equivalent to more than 17,600 years of conventional laboratory research. The aggregated dataset created the first global benchmark for human spatial navigation ability, stratified by age, gender, and country of origin. More consequentially, it identified that carriers of the APOE4 gene — the strongest known genetic risk factor for Alzheimer's — navigate with measurably less efficient routes, a difference detectable years before any clinical symptoms appear. These findings have been published in Nature and PNAS, establishing the game as a legitimate scientific instrument. The Academy hosts Sea Hero Quest in the Mind School because its central exercise is collective intelligence: the individual player's wayfinding, unremarkable in isolation, becomes — when aggregated across millions — an instrument of scientific discovery that no single laboratory could have produced.