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games, experiments & simulations
209 ways to procrastinate responsibly
























































































































































































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whatifs.fun is a collection of 300+ free online games, brain tests, interactive experiments, and simulations — all playable instantly in your browser with no download or signup required. From reaction time tests and memory challenges to nuclear explosion simulators and deep ocean explorers, every experience is designed to surprise, educate, and entertain.
Our games span categories including cognitive and brain tests (memory test online, chimp test, verbal memory), speed and reflex challenges (reaction time test, typing speed test, CPS test), vision and perception tools (color blind test, peripheral vision test), knowledge quizzes (true or false, higher or lower, country outline quiz), interactive thought experiments (trolley problem, spend a billion dollars), and scale visualizations (size of space, ocean depth explorer). Whether you want to test your reflexes, challenge your memory, or explore how the universe works, there’s something here for you.
All games are mobile-responsive browser games — no download needed, no accounts, no ads. New experiences are added regularly. Check out our blog for deep dives into the science and stories behind each game.
Last updated: April 2026 · whatifs.fun — Free interactive games, experiments & simulations