gametree-score-regexp

gametree-score-regexp is a variable defined in `gametree.el'.
Its value is

"[^\n
]*\\({score=[ 	]*\\(![ 	]*\\)?\\([-+]?[0-9]+\\)}[ 	]*\\)[\n
]"

Documentation:
Regular expression matching lines that guide the program in scoring.
Its third parenthetical group should match the actual score. Its
first parenthetical group should match the entire score tag. Its
second parenthetical group should be an optional flag that marks the
line as *manually* (as opposed to automatically) scored, which
prevents the program from recursively applying the scoring algorithm
on the subtree headed by the marked line, and makes it use the manual
score instead.

You can customize this variable.