This PDF of a classic Star Ace supplement is generated from scans of the product. Originally published in 1985 by Pacesetter, Precis Intermedia brings this accessory for the classic sci-fi RPG to this site, under license from Ronin Arts.

From the back cover:
Aliens is a collection of stories and descriptions of facinating alien worlds and the creatures who inhabit them. Join Balik the Kleibor and Guba the Trakan as they explore faraway planets and bizarre societies and cultures. Aliens, however, is more than a guided tour: each planet in this book can provide players with dozens of exciting adventures for the Star Ace roleplaying game. So prepare yourself -- there are worlds to discover!