The Introduction begins by letting you know what you are getting into (if it is a bit of a shock to be called a 'maggot' in the opening sentence, be glad you haven't really enlisted!). In this work, there's enough of an overview of the setting and rules to let you play through the scenario provided, and six pregenerated characters with which to do so. It's a good way to find out if you like this particular science-fiction action/horror game before parting with any money.
The setting is familiar to anyone who's watched the Alien movies, especially the second one (Aliens). Characters are members of the Colonial Marine Corps in the year 2450, in a future that saw Earth abandoned in 2200 (for reasons that are left to the GM to determine, but you don't need to worry about that now. Some of the former colonies have banded together to form the Colonial Dominion, of which the Colonial Marines are the military arm. The rest are rebel scum, of course! Only one lot of sentient aliens has been encountered so far, or at least that's what official reports say.
Then Chapter 1: Rules and Setting begins with a collection of terms and concepts, a ready-reference for Corps jargon and current technology, followed by 'Basic Rules and Regs' which summarises enough of the rules to let you play the game. It's all based around Abilities, of which there are eight. They've been given rather silly names but boil down to describing how smart, strong, tough, good with weapons and so on each character is. There are also Aspects, which put an individual spin on things for each character. He also needs a Gear Loadout, the equipment and weapons that enable him to survive.
There are two sorts of scenes: action scenes and narrative scenes. Narrative scenes are descriptive, often covering large periods of time, and there is little or no need for recourse to the game mechanics. Action scenes occur when danger is about, and can get fast and furious... and then it's time to get the dice out. Outcomes are determined by rolling a d6 and adding the appropriate Ability, with - of course - a range of modifiers as appropriate, and comparing what you get with a Target Number - which, if you are fighting, will be what your opponent rolled. Of course there's more: range, weapon effects and such like need to be taken into account. There are some summary charts and tables that come in handy when you actually start to play.
Next, Chapter 2: Personnel Files presents six ready-to-play Marines. As well as their statistics (which have notes about what they mean right there beside them, very useful), there are similarly-annotated gear lists and some background to help you get a feel for the character. Although they have been named, only a first initial has been given so you may choose whether the one you play is a bloke or a bird. Interestingly, all have led troubled lives and messed up somewhere along the line, and have now been drafted into a penal legion... beats gaol time, I suppose!
Finally, the adventure 'Trial by Fire' builds on the fact that all the characters have a criminal record. After basic training, the squad was shipped out in coldsleep for 'advanced training' - an automated facility where they, and others, will be tested. In essence it's a puzzle dungeon designed to test teamwork and reliability - something the Corps wants to know about this squad before sending them into REAL combat. The map is for the GM alone, 'cos it shows all the traps. And the nasty things that might be unleashed...
The system suits fast and furious action, and the GM is supplied with tracking sheets to keep on top of everything. The adventure itself is an artificial situation, but it's intended to be one... and the GM has considerable leeway as to how to use the resources provided against the squad. Keep things moving, this scenario isn't much of a one for character development and interaction: play it for what it is and have a blast!