If you're a fan of free retro PC games, then Christmas has come early as digital distribution site GOG is handing out I Have No Mouth And I Must Scream as a freebie until December 25. Adapted from a short story written by acclaimed author Harlan Ellison, the game is a disturbing journey to the center of the planet, where humanity's last survivors have been imprisoned and kept alive for over a century by the sadistic supercomputer AM.

Each of the game's five characters have their own dark secrets that you'll need to uncover. There are plenty of mysteries to solve in this point-and-click cult-classic from 1995, and if you fail to escape from the lair of AM, you'll discover in horrifying detail why the game has such a weird title.

As a GOG product, I Have No Mouth And I Must Scream also comes with a few extras such as digital scans of the original manual, a short documentary on how it was made, and the original soundtrack that was produced by John Ottman, the composer behind the hit film The Cable Guy. It's a great soundtrack that's playing when Jim Carrey torments Ben Stiller.