"Metal Slug 7 (メタルスラッグ 7) is a run and gun video game developed by SNK Playmore for the Nintendo DS, PlayStation Portable and Xbox Live Arcade. It is the eighth title in the main Metal Slug series. It was announced in the September 2007 issue of Famitsu and marks the first game in the main series that will be released without an arcade version. The game was released in Japan on July 22, 2008 and North America on November 28, 2008 by Ignition Entertainment.
A revised version of the game, titled Metal Slug XX (メタルスラッグ XX), also known as Metal Slug Double X, was released on December 23, 2009 in Japan and North America on February 23, 2010 by Atlus for the PlayStation Portable. This version of the game features additional content, including co-op multiplayer and downloadable content. Metal Slug XX was also released on Xbox Live Arcade on May 19, 2010."
Source: Wikipedia, Metal Slug 7 , available under the CC-BY-SA License.