It's not every day that a previously unseen game comes out for the Nintendo Entertainment System ( hipsterish modern ports notwithstanding ). One of those days occurred late last week, though, as a long-lost playable prototype ROM of was released on the Internet 25 years after its original creation.

Nintendo Player goes into extensive detail on the game's creation, which was based off of a movie of the same name by TV cartoon production company Filmation (creators of He-Man). The Happily Ever After film, a pseudo-sequel to the famous "Snow White" fairy tale, was originally planned for 1991 but didn't come out until 1993 due to legal and financial issues. When the movie promptly flopped (and when its distributor became embroiled in an SEC fraud investigation), the accompanying NES game that had been developed by Japanese studio SOFEL (Wall Street Kid, Casino Kid) was shelved.

Though a very different SNES version was released by a different developer in 1994, the NES game was thought lost forever, save for a few stray screenshots in magazines and reports from Consumer Electronics Shows past. That is until Sean McGee (who previously unearthed a long-lost Super Mario Bros. 2 sample cartridge) found and purchased a prototype from an Austin-area private seller. Rather than selling the rare game to the highest bidder, as is common with many discovered NES prototypes, McGee dumped the ROM to allow everyone to play this lost gem free on an emulator.

Although it's officially a prototype, the game seems pretty complete, with four full stages that culminate in a series of bosses. Despite the childish fairy tale setting, the game is fiendishly tough in that unforgiving and classic NES style. Snow White's main attack is a spinning cape move with an extremely limited range, and she can only take five hits before having to use one of four limited continues. While the graphics are pretty basic (even for the 1991-era NES), there's a pretty catchy soundtrack and some interesting navigational magic powers at play, too. As Nintendo Player puts it, "as far as unreleased Nintendo games go, this has to be one of the best."

For NES obsessives, Happily Ever After's release is probably the biggest discovery since a playable copy of Bio Force Ape surfaced in 2011 (retro game enthusiast Danny Cowan called that discovery "the end of an era"). But those prototype hunters aren't done scouring the world for more unreleased cartridges. There are dozens of other NES games that were teased in the press but never saw release, some of which seemed more or less complete based on available information. Who knows what other retro titles might be lurking out there at your local yard sale.