The Library of Congress believes it's found the source code to a never-released version of handheld game Duke Nukem: Critical Mass, unearthed from a trove of games submitted for copyright registration. Critical Mass came out for the Nintendo DS in 2011. It was originally supposed to be the start of a new trilogy, but it was released to terrible reviews, and its big brother Duke Nukem Forever didn't do much better. Unsurprisingly, future games were scuttled. But in a blog post, Library of Congress staff member David Gibson recounts finding a title that never even saw release: a PSP version of the game that was significantly different to its Nintendo counterpart. Gibson is still trying to reconstruct the game, but he's found game music and even pieced together a basic 3D model of Duke in a jetpack.

Every work is automatically granted copyright in America, but in order to sue for damages, authors have to officially register with the Library of Congress, sending copies of their book, game, movie, or other project to be examined and potentially held in perpetuity. As digital materials become more common, it's become one of the few places that unambiguously has the rights to permanently store otherwise ephemeral media, though not everything gets a place in the library's archives. Video games and other software, which are highly dependent on hardware that degrades and becomes obsolete, are a particular challenge for archivists, whether at the Library of Congress or a museum or private collection.

Granted, even fans of the franchise were never on tenterhooks for footage from Critical Mass. This does, however, add another chapter to the saga of a series whose enigmatic ghost has managed to come back year after year. Gamers spent over a decade looking through trailers and leaked footage from Duke Nukem Forever. When the game finally came out in 2011, it seemed like there was nothing left to watch for. But apparently, Duke still has some secrets left. And the Library of Congress has made good on its goal of being a repository of knowledge that the rest of the world would probably prefer to forget.