From publisher blurb:
The Galaxy Just Got Bigger!
Daring Men of Tomorrow and intrepid Deep Space Explorers face off against a horde of savage White Simians in the floating jungle of a lost world. Plucky Sidekicks escape relentless Bounty Hunters aboard their modified skyboards. Somewhere on the edge of the galaxy, an Orbital Battle Station is about to obliterate an entire planet with the push of a button.
The White Star Companion brings nearly one hundred pages of new options to your White Star: White Box Science Fiction Roleplaying experience. New classes, new aliens, new creatures, new weapons, and new starships are all revealed. Complete rules for planetary vehicle combat are provided along with ways to generate complete star systems simply by rolling a few dice. The brand new skill and Serial systems can instantly flesh out a character's history and talents.
With the White Star Companion, you'll expand your game to the edge of the galaxy and beyond! White Star: White Box Science Fiction Roleplaying is completely compatible with Swords & Wizardry WhiteBox and many other old-school roleplaying products.