If you play Cepheus Engine or Mongoose Traveller and you want to surprise your players with a certain iconic alien lifeform, this is the supplement to get. The book details a variety of "evoled" xenomorphs, that is, they have new features that make them a little different then the stock aliens. This includes some which breathe fire, other which create spores, or others which are puppeteers. Each one has a full explanation of their lifecycle and the game stats you need to terorrize your unsuspecting adventurers. It also includes a small 40-50 person mining colony which is being terorrized by the aliens. It has full maps and stats for the colony and colonists. I highly recommend it.