Konami have announced today that their highly popular stealth-action series, Metal Gear, has achieved life-to-date sales of 31.1 million units. The announcement coincided with the Smithsonian American Art Museum’s decision to display two Metal Gear games; Metal Gear Solid and Metal Gear Solid 2: Sons of Liberty as part of their “The Art of Video Games” exhibition. The exhibition is one of the first to present games as art, acknowledging their evolution and impact on other media. The Metal Gear series will reach its 25 year anniversary in July.