This is problematic for many of the same reasons the sequence game is problematic. "simpler rule" is really hard to define in a way that still makes the game fun.

(I take it as given that you are modifying the game to play two games simultaneously of course)

How's this? The student may end the game at any point. In this case the master scores 10 and the student 0. Scale the other scoring mechanisms and weight them so that the student in general should gain significantly more than a -10 point differential whenever the master is not trying to make an ubercomplex rule.