Games module errors when completion is enabled

When a game is implemented (in my case, Millionaire) with activity completion enabled, such as "must receive a grade" the following error is generated

Debug info: Module game claims to support
FEATURE_COMPLETION_HAS_RULES but does not have required
game_get_completion_state function
Stack trace:

line 1337 of /lib/completionlib.php: moodle_exception thrown
line 582 of /lib/completionlib.php: call to completion_info->internal_systemerror()
line 497 of /lib/completionlib.php: call to completion_info->internal_get_state()
line 1279 of /lib/completionlib.php: call to completion_info->update_state()
line 811 of /lib/grade/grade_grade.php: call to completion_info->inform_grade_changed()
line 232 of /lib/grade/grade_object.php: call to grade_grade->notify_changed()
line 741 of /lib/grade/grade_grade.php: call to grade_object->update()
line 1634 of /lib/grade/grade_item.php: call to grade_grade->update()
line 287 of /lib/gradelib.php: call to grade_item->update_raw_grade()
line 498 of /mod/game/lib.php: call to grade_update()
line 1026 of /mod/game/locallib.php: call to game_grade_item_update()
line 687 of /mod/game/locallib.php: call to game_save_best_score()
line 587 of /mod/game/millionaire/play.php: call to game_updateattempts()
line 62 of /mod/game/millionaire/play.php: call to game_millionaire_OnAnswer()
line 22 of /mod/game/millionaire/play.php: call to game_millionaire_play()
line 206 of /mod/game/attempt.php: call to game_millionaire_continue()
line 176 of /mod/game/attempt.php: call to game_create()
line 25 of /mod/game/attempt.php: call to game_do_attempt()