Your points keep decaying.
Solve to stabilize them before they hit zero.
(best: 0)
🏅 New achievement unlocked
Your points don't drop by a fixed amount per second — they shrink by a fixed percentage of whatever they currently are, continuously. That's exponential decay, and it follows the same formula used to describe how a radioactive substance loses mass over time: N(t) = N₀ × (1/2)^(t / half-life), where N₀ is the starting amount and "half-life" is how long it takes to fall to half its current value. Because the percentage is constant but the base keeps shrinking, the actual amount lost per second gets smaller as your points get lower — the curve flattens rather than hitting zero in a straight line, right up until it does.
The game runs this formula every single animation frame using your current half-life value, which starts at 15 seconds and drops by one second every 5 correct answers in a row (down to a 5-second floor) — a shorter half-life means the same percentage loss happens more often, so the curve gets visibly steeper at higher levels even though the underlying math never changes. A correct answer doesn't add points on a fixed schedule; it both restores some points immediately and pauses the decay formula entirely for 3 seconds, which is the one part of the game that's a pure gameplay mechanic rather than a model of anything physical — real radioactive decay can't be paused by solving a percentage problem.
N(t) = N₀ × (1/2)^(t / half-life) — the same exponential-decay formula used for radioactive isotopes, running continuously in the background every frame using your current half-life. It's why the points bar drops fast at first and slows down as it gets lower: the loss is always a percentage of the current value, not a fixed amount.
Every 5 correct answers in a row shortens your half-life by 1 second (down to a 5-second minimum), and a shorter half-life means the same percentage drop happens more frequently — so the curve gets steeper at higher levels even though the formula itself never changes, only the half-life value plugged into it.
Both — a correct answer immediately restores some points and also freezes the decay formula for 3 seconds, giving you a brief window where the curve goes flat instead of down. That freeze is a gameplay mechanic, not a model of real radioactive decay, which can't be paused by anything; it's there to reward a correct answer with breathing room, not to represent real physics.
Your points decay exponentially all the time, even while you're thinking.
Answer the percentage questions correctly to recover points and stabilize the decay for a few seconds.
Some questions are traps: one option looks easy but is wrong. Watch the card's border — sometimes it looks different.
The game ends when your points reach zero.