You start with six balls. You start from three feet. You putt from three feet until you make a putt. If you make the putt, you take that ball and all remaining balls back three feet. If you miss, that ball or "life" is lost. Your "score" is the farthest distance at which you make a putt. So for example:
Make from 3'. Six balls remain. Make from 6'. Six balls remain. Miss, miss, make from 9'. Four balls remain. Two lives lost. Miss, make from 12'. Three balls remain, one life lost. Miss, miss, miss from 15'. Your score is 12'.