Bowling Game

Logic details

Bowling is played by throwing a ball down a narrow alley toward ten wooden pins. The objective is to knock down as many pins as possible per throw.
The game is played in ten frames. At the beginning of each frame, all ten pins are set up. The player then gets two tries to knock them all down.
If the player knocks all the pins down on the first try, it is called a "strike,“ and the frame ends.
If the player fails to knock down all the pins with his first ball, but succeeds with the second ball, it is called a "spare“.
After the second ball of the frame, the frame ends even if there are still pins standing.
A strike frame is scored by adding ten, plus the number of pins knocked down by the next two balls, to the score of the previous frame.
A spare frame is scored by adding ten, plus the number of pins knocked down by the next ball, to the score of the previous frame.
Otherwise, a frame is scored by adding the number of pins knocked down by the two balls in the frame to the score of the previous frame.
If a strike is thrown in the tenth frame, then the player may throw two more balls to complete the score of the strike.
Likewise, if a spare is thrown in the tenth frame, the player may throw one more ball to complete the score of the spare.
Thus the tenth frame may have three balls instead of two.