public class GameComparer : IEqualityComparer<XElement>
    {
        public bool Equals(XElement x, XElement y)
        {
            return x.Attribute("name").Value == y.Attribute("name").Value;
        }

        public int GetHashCode(XElement obj)
        {
            return (obj == null ? 0 : obj.GetHashCode());
        }
    }

    class XmlMerge
    {
        public static XmlDocument Merge(string xml1, string xml2)
        {
            XElement root1 = XElement.Parse(xml1);
            XElement root2 = XElement.Parse(xml2);

            StringBuilder s = new StringBuilder();

            IEnumerable<XElement> games1 = from a in root1.Elements("game") select a;
            IEnumerable<XElement> games2 = from b in root2.Elements("game") select b;
            IEnumerable<XElement> games = from g in games1.Union(games2).Distinct() select g;
            s.Append("<?xml version=\"1.0\"?>");
            s.Append("<menu>");
            foreach (XElement el in games)
            {
                s.Append(el);
            }
            s.Append("</menu>");
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(s.ToString());
            return doc;
        }
    }

IEnumerable<XElement> games = from g in games1.Union(games2).Distinct() select g;

IEnumerable<XElement> games = from g in games1.Union(games2).Distinct(new GameComparer()) select g;