Groundfall

Groundfall helps teachers and students study what nuclear weapons do, using the declassified physics behind them. Place a weapon on any city and see its blast, heat, radiation and fallout ring by ring. Every figure states where it comes from and what it leaves out. Built for the classroom Teaching projects (Full Access): ready-made lessons with sourced readings, teacher notes, maps that open on the scenario, and printable PDF handouts. Evidence Lab (Full Access): students answer a question, read primary sources, then answer again, and keep both answers in a notebook. 18 chapters on the science, history and policy of nuclear weapons, each with an "In depth" layer for older students. Available in English, French, Spanish and Italian. The simulator Blast, heat and fireball ranges calibrated against Glasstone & Dolan, The Effects of Nuclear Weapons (1977), and Brode's airblast fit. Shock-wave arrival times, tested against the book's own worked examples. Airburst or surface burst, with a wind-oriented fallout plume and the 7-10 decay rule. Illustrative casualty ranges anywhere on Earth, from the GHS-POP 2025 population grid (European Commission JRC). The range shows how much the result depends on the assumed rates; it is not a forecast. Tap any ring to see what happens there and when. Free and Full Access Free: Little Boy and Fat Man as often as you like, every Learn chapter, the Prepare guide and two conflict scenarios. Full Access, one purchase with no subscription: all 89 weapon presets, custom yield, every scenario, the PDF briefing, Evidence Lab and Teaching projects. Honest about its limits Groundfall is an educational illustration, not a prediction. Burst height is modelled as airburst or surface only, casualty rates are fixed assumptions, the population grid counts where people live rather than where they are during the day, and fallout is a simplified plume, not a radiation dose map. The app says so beside the numbers. Simulations run on the device. City searches contact a geocoding service, and the map provider receives map requests. No account, no ads, no behavioural tracking; crash reports go to Sentry without screenshots.