qmk_firmware_custom/keyboards/handwired/gamenum/gamenum.h

#pragma once

#include "quantum.h"

#define KEYMAP( \
    k00, k01, k02, k03, \
    k10, k11, k12, k13, \
    k20, k21, k22,        \
    k30, k31, k32,        \
           k41, k42, k43  \
) \
{ \
    { k00, k01, k02, k03}, \
    { k10, k11, k12, k13}, \
    { k20, k21, k22, KC_NO}, \
    { k30, k31, k32, KC_NO}, \
    { KC_NO, k41, k42, k43}  \
}