Overview
Roll 1 or 2 dice and then cross out pins equal to the total (e.g. with 5 you could cross out 2 & 3 or 4 & 1)
Keep rolling until you cannot make a valid cross out (e.g. with a 4, cross out 3 and 1, but as 3 was used in last example, you have to stop)
You then get to start a second roll phase, but keep the same crossed out pins
Once you cannot make a valid cross out on the second roll, your turn ends
Scoring
You score for the quantity of pins crossed out in a turn
Two bonuses are afforded
a) Crossing out all 10 pins with ball 2 gives you a score of 10 + the next first attempt's score
b) Crossing out all 10 pins with ball 1 gives you a score of 10 + the score of both attempts on your next turn
Extra Help
You may click on the depicted bowling ball to add or subtract 1 from your current roll