$context['arcade_viewing'] is only defined in the arcade it self no where else so it wont wotk just by puttting $context['arcade_viewing'] in your template
you can do this however in boardindex.php
after
$context['show_calendar'] = false;
add
global $smcFunc;
$context['arcade_viewing'] = array();
$context['arcade_num_viewing'] = array('member' => 0, 'guest' => 0, 'hidden' => 0);
// Search for members in arcade
$request = $smcFunc['db_query']('', '
SELECT
lo.id_member, lo.log_time, lo.url, mem.real_name, mem.member_name, mem.show_online,
mg.online_color, mg.id_group, mg.group_name
FROM {db_prefix}log_online AS lo
LEFT JOIN {db_prefix}members AS mem ON (mem.id_member = lo.id_member)
LEFT JOIN {db_prefix}membergroups AS mg ON (mg.id_group = CASE WHEN mem.id_group = 0 THEN mem.id_post_group ELSE mem.id_group END)
WHERE INSTR(lo.url, {string:url}) ',
array(
'url' => 's:6:"action";s:6:"arcade"',
'session' => $user_info['is_guest'] ? 'ip' . $user_info['ip'] : session_id(),
)
);
while ($row = $smcFunc['db_fetch_assoc']($request))
{
if (empty($row['id_member']))
{
$context['arcade_num_viewing']['guest']++;
continue;
}
if (!empty($row['online_color']))
$link = '<a href="' . $scripturl . '?action=profile;u=' . $row['id_member'] . '" style="color: ' . $row['online_color'] . ';">' . $row['real_name'] . '</a>';
else
$link = '<a href="' . $scripturl . '?action=profile;u=' . $row['id_member'] . '">' . $row['real_name'] . '</a>';
$is_buddy = in_array($row['id_member'], $user_info['buddies']);
if ($is_buddy)
$link = '<b>' . $link . '</b>';
// Add them both to the list and to the more detailed list.
if (!empty($row['show_online']) || allowedTo('moderate_forum'))
{
$context['arcade_num_viewing']['member']++;
$context['arcade_viewing'][$row['log_time'] . $row['member_name']] = empty($row['show_online']) ? '<i>' . $link . '</i>' : $link;
}
if (empty($row['show_online']))
$context['arcade_num_viewing']['hidden']++;
}
$smcFunc['db_free_result']($request);
krsort($context['arcade_viewing']);
then you can call it in your template like
echo' ', implode(', ', $context['arcade_viewing']), '';
if you wanted it to show guest and spiders and thumbnail you could install my arcade who mod but you still have to make an edit to boardindex.template.php