1. Make a glossary of terms.
2. Make a crossword game instance using that glossary.
3. When finished making crossword entries, click the "End of crossword game" button
4. The following error is thrown (Debugging level "DEVELOPER"

Debug info: Module game claims to support
FEATURE_COMPLETION_HAS_RULES but does not have required
game_get_completion_state function
Error code: err_system
Stack trace:
line 1256 of /lib/completionlib.php: moodle_exception thrown
line 593 of /lib/completionlib.php: call to completion_info->internal_systemerror()
line 517 of /lib/completionlib.php: call to completion_info->internal_get_state()
line 1187 of /lib/completionlib.php: call to completion_info->update_state()
line 836 of /lib/grade/grade_grade.php: call to completion_info->inform_grade_changed()
line 253 of /lib/grade/grade_object.php: call to grade_grade->notify_changed()
line 765 of /lib/grade/grade_grade.php: call to grade_object->update()
line 1692 of /lib/grade/grade_item.php: call to grade_grade->update()
line 284 of /lib/gradelib.php: call to grade_item->update_raw_grade()
line 500 of /mod/game/lib.php: call to grade_update()
line 433 of /mod/game/lib.php: call to game_grade_item_update()
line 689 of /mod/game/locallib.php: call to game_update_grades()
line 175 of /mod/game/cross/crossdb_class.php: call to game_updateattempts()
line 111 of /mod/game/cross/crossdb_class.php: call to CrossDB->game_cross_computecheck()
line 104 of /mod/game/cross/play.php: call to CrossDB->loadcross()
line 18 of /mod/game/cross/play.php: call to game_cross_play()
line 124 of /mod/game/attempt.php: call to game_cross_continue()
line 25 of /mod/game/attempt.php: call to game_do_attempt()