You probably need to wrap $hid
in quotes like so:
$peoplewhomatch = mysql_query("SELECT x.id_customer, g.title Have, c.user_name as Member, g.title gwants, gg.title Has, y.id_customer x_username
FROM Want x
JOIN Want y
ON (y.id_sellversion,y.id_version) = (x.id_version,x.id_sellversion)
inner join Version as v
on x.id_version = v.id_version
inner join Version as vv
on y.id_version = vv.id_version
inner join Game as g
on g.id_game = vv.id_game
inner join Customer as c
on y.id_customer = c.id_customer
inner join Game as gg
on gg.id_game = v.id_game
WHERE x.id_have = '$hid'
ORDER BY x.id_have
LIMIT 0, 30")or die("Query failed: " . mysql_error());