(by  Bob Anderson)

You starts with 27 points.

You throw 3 darts on every double segment from 1 to bull. If you miss a segment with all 3 darts, the double value of the according segement
is subtracted from your score. Every succesful throw adds the double value to the score.
If you drop to or below 0, the game ist lost.

 

Example: 

Round 1: Doublel 1 - no hit. new score= 27 - 2 = 25 points

Round 2: Double 2 - 2 hits -> new score= 25 + 2*4 = 33 points

Round 3: Double 3 - no hit -> new score = 33 - 6 = 27 points

and so on...