MPF machine variable
Holds the numeric value of a player's score from the last
game. The "x" is the player number, so this actual machine
variable is player1_score or player2_score.
Since these are machine variables, they are maintained even after a game is over. Therefore you can use these machine variables in your attract mode display show to show the scores of the last game that was played.
These machine variables are updated at the end of the game, and they persist on disk so they are restored the next time MPF starts up.