there's one bomb at a time. its fuse is a countdown, and everyone watches the same clock.
burn $FUSE to add time: a minute per 0.0005 ETH, never more than 24 hours on the clock.
90% of every light burns now. 10% is sealed in the bomb, waiting.
at zero the whole vault burns. the last lighter gets the Last Match badge, forever. a new bomb starts.