User summary: The Alien Dawn Gamemaster Handbook is the principle document providing the science fiction genre mechanics for the game system. The document was created about 1991 and released in various formats prior to the 1996 version. The final version of the Gamemaster Handbook was published as a series of fourteen WordPerfect documents in a ZIP archive. Roughly simultaneously, the material was released in a series of ASCII text files. The Gamemaster Handbook provides rules for Aliens (including technology, weapons, and spaceships), tips for campaign management, and methods to use cards (distributed separately) to randomize events. It also includes a bestiary. The bulk of the book, however, is devoted to combat which occurs in phases and is played with scale miniatures. Combat includes everything from archaic weapons to futuristic vehicle combat.