Get this. Get it if you GM White Star, get it if you ref Traveller and get it if you GM Hulks and Horrors. Lots of player classes (I like the Changeling and the Alien Psychic Weapon, oh, and the Plant-Like Lifeform the best). A metric buttload of tables for time-pressed GMs rounds out the last half of this book in a very good way. Events, places and other setting dressing automate things for you.
[5 of 5 Stars!]