<?php

function dbwp_add_custom_metabox() {

    add_meta_box(
        'dbwp_meta',
        'Upcoming Game',
        'dbwp_meta_callback',
        'game',
        'normal',
        'core'
    );

}
add_action('add_meta_boxes', 'dbwp_add_custom_metabox');

function dbwp_meta_callback() {
    ?>

    <div>
        <div class="meta-row">
            <div class="meta-th">
                <label for="game-id" class="dbwp-row-title">Game ID</label>
            </div>
            <div class="meta-td">
                <input type="text" name="game-id" id="job-id" value="">
            </div>
        </div>
    </div>

    <?php
}