The ornamental design for a gamecontrollerattachment, as shown and described.
FIG. 1 is a front, top and right side perspective view of a game controller attachment showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof, the left side being a mirror image hereof;
FIG. 5 is a plan view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is a sectional view taken along line 7—7 of FIG. 2, internal elements being omitted; and,
FIG. 8 is a perspective view thereof, showing the game controller attachment in its environmental use, the broken lines showing of the electronic game apparatus being for illustrative purposes only and forming no part of the claimed design.