"The Sole button"
You are in a sealed room with 100 strangers. In front of each person is a button. EDIT: NO one can see eachother and their actions.
The rule:
exactly one person must press their button.
If nobody presses it, everyone dies.
If only one person presses it, Everyone lives
If more than one person presses it, everyone who pressed dies - but the rest survive.
There is no way to communicate. You have 60 seconds. What do you do?