[FurnaceFace]

Excellent game to play. As for the origins of the scoring:

Background of Tennis Scoring
As for the history of tennis scoring, there are two background stories:
1. that it has its origin in medieval numerology. The number 60 was considered to be a "good" or "complete" number back then, in about the same way you'd consider 100 to be a nice round figure today. The medieval version of tennis, therefore, was based on 60--the four points when 15, 30, 45 (which we abbreviate to 40) and 60, or game.
2. The system may be based on the presence of a clock face at the end of the tennis court. A quarter move of the appropriate hand was made after each rest, with the score being called as 15, 30, or 45. As the hand was moved to 60, this was the game. This didn't explain a score of 40, however.

http://www.all-about-tennis.com/tennisscoring.html