This is a bold move by Mongoose to use their Traveller system, deviating from traditional Traveller products as it adapts the mechanics and ramps up the equipment details to root players in a Wild West setting - as opposed to just applying generic backwater world "Low Tech Level" brush.
Many years back I remember playing a character in a GDW Traveller game which was based in the Aliens films, and suddenly the shotgun had extra significance because that was a "back-up" weapon in the film. Usually in games like Traveller and Time Master weapon definitions seemed defined by their comparative limitations to the high-tech weaponry, create a concept of equipment or resource-"lack" when a new setting is applied to a what could be a universal system (does that makes sense? Redactive semiotics?). For many years I was suspicious of the GURPs core rules because I favoured games primarily based on genres/settings as opposed having universally applicable core mechanics. Funnily enough I find myself revisiting these ideas "universal (customised) vs. pure setting" every time I look at Chaosium's BRP and multi-genred Savage Worlds game. The answer, of course, is a good, is to publish well fleshed-out settings supplement (the irony here, is that Palladium and several other publishers in the 80s used the similar systems throughout their games but the games were sold on setting, not the system - well, sort mostly). If you're a loyal fan of the imperial galactic "feel" of the Classic Traveller canon, this might not appeal as a Traveller product per se, but if you like the Mongoose Traveller system and have a relaxed approached the gaming you will possibly enjoy the extra gloss and grit of cinematically style cowboys and their feisty female companions. Come to think of it, Firefly isn't that far of all of this, aesthetically speaking only, but we're really talking about Cowboys and Aliens, or a Western with a two-way Alien ("Xenomorph") hunt - not a backwater colony beyond Federation Space - this is firmly Wild West Earth Pulp.
As well as adventure details (the "Town of Bent River"), there's even the class / career of "Desperado" and a bunch of fully equipped pre-generated characters which actually makes this a "pick-up-and-play" supplement in my book. Even your horse can have a personality quirk - which reminds us that horses in some ways are NPCs or hirelings with relationships to the characters in their own special way. Not to mention the fact that horse-riding can be dangerous in itself - but this is optional stuff.
It's a great little supplement (50 pages), and if you don't own any games with Western/cowboy settings, there's a fair about which can be "mined" for other systems.
One of my problems with this product is that if you follow the introductory instructions to the letter, your game will be flawed due to it's the premise that the players (not characters) shouldn't know or suspect a sci-fi element:
"Referees should take pains at not telling the players the title
of this adventure, as the presence of aliens in the Wild West
should be sprung upon them. Instead, tell them it is called
something like The Last Ride of McCreedy, or The Rise of the
Sioux, or anything that does not have the words xenomorph or
alien in it! The adventure starts off like a normal Wild West tale,
but things can get weird very quickly!" p1
My point here is that your players will probably not be convinced that you've chosen Traveller over other systems to play a Wild West game ("You lost your copy of Boot Hill... and dont think Savage Worlds is a better choice?"). The good news is that being a role-playing game the players can enjoy playing naive or misguided character (Knowledge checks will reveal that Sioux hatchets don't make wounds like that, and what are these burns..? etc). This is what is commonly referred to as the "player-knowledge verses character-knowledge" paradigm, and is in RPG Class 101. It's important that players trust the Referee or the contract of imagination can be broken - especially important when you start messing around with genres! Tread carefully when crossing the streams. ;)
My other almost-gripe is the price. I was pretty curious about this product and was really happy to receive a review copy. Although I'm not currently playing a Traveller campaign, my curiosity was prepared for be to spend maybe 5-6 dollars at the most for a PDF. $9 makes sense if you think about it as a campaign sourcebook as opposed to just an adventure - it's sort of a springboard with benefits - much like an introductory scenario - I haven't check the price of the hardcopy, I guess $9 is a fair price.
If your enthused by Traveller and Cowboys and Aliens (or Alien but with a lot of dust) this is a must-buy. If you think you can do something like with you're own choice of system, there just might be the odd little detail which will improve your game.
I'm very drawn to notion of the Giger's Alien styled "xenomorph" vs. the Magnificent Seven. ;)
Full marks for ambition and style!