<?php

if(!empty($_POST['height']) && !empty($_POST['width']) && !empty($_POST['color']) {
   echo '
<textarea readonly="readonly" cols="60" rows="2"><iframe src="oyun.php?id=', $_POST['id'], '&width=', $_POST['width'], '&height=', $_POST['height'], '" width="', $_POST['width'], '" height="', $_POST['height'], '"></iframe></textarea>';
}

?>

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
   <input type="hidden" name="id" value="<?php echo $_GET['id']; ?>" />
   <input type="text" name="width" />
   <input type="text" name="height" />
   <input type="text" name="color" />
</form>