The ornamental design for a portion of a pedal-based game controller, as shown and described.
FIG. 1 is a front perspective view of the portion of a pedal-based game controller showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a left view thereof;
FIG. 4 is a top view thereof; and,
FIG. 5 is a top view thereof.
The broken line showing of the remainder of the portion of a pedal-based game controller is for illustrative purposes only and forms no part of the claimed design.