1. Each scene hides four clues, marked with a pulsing ring. Click one to open its case file.
2. Decide how to file it: a known cause of lung cancer (IARC Group 1), a probable cause (Group 2A), or no evidence. A wrong choice costs nothing: you get the explanation and can try again.
3. Real hazards can be fixed. Every fix raises the clean-air score.
4. Somebody in each scene wants to talk. Pick the reply you think is right.
5. When all clues are filed, the case closes and the next one opens. Three cases, then your report.

The game shows whether something can cause lung cancer in people in general. It cannot tell anyone what caused their own illness, and most people with these exposures never develop lung cancer.

Settings are kept on this device only.