GN writes: "Metal Slug XX has a curious title. Have I really paid so little attention to this Contra-clone that they've managed to release twenty of these games? Is this a brand new Metal Slug spin-off that I should know about? It turns out that Metal Slug XX is actually an updated version of Metal Slug 7, the two year old Nintendo DS action game. The name (pronounced "Double X") is a call back to the original Metal Slug X, which in turn was an updated version of Metal Slug 2."