If there's an example of the free-rolling irrational craziness that is the Rifts universe encapsulated in a single book, Thundercloud Galaxy is probably a good example. As far as a product goes, it's prett standard Palladium fare, which is to say quite well made. There's 160 pages of nicely bound two-colum justified serif font, with tiny centered sans-serif page numbers. There is a pretty comprehensive table of contents, but no index. The black and white artwork throughout is of fair to good quality in terms of technique, but of limited imagination. Some of the more notable pieces, like the leggy blonde wearing nought but a pair of tiny knickers whilst summoning some alien demon, are just downright stupid. The colour cover of a power-suited human wrestling some alien swamp creature is quite good. The writing is highly informal to the point of rambling, and the organisation of the text pretty good (background, major species, other critters, exotic technology, colony creation, adventures).
The background to the Thundercloud Galaxy is painful to read. It displays an immaturity that can occasionally be amusing when done in utter parody, a Thanatos-loving story of death and destruction on a scale beyond the Biblical. Sure, Rifts does this as well, with its hostile aliens, dimensional beings, and the joys of a nuclear war for good measure. But in Thundercloud Galaxy, an quixotic alien species known as "The Dominators" created a 'Black Hole Projector' that almost completely destroyed life in the entire galaxy. The motivations of these interstellar psychopaths is quite unfathomable - as is their capacity to hold a civilisation together long enough to even build such a device. Such is the precursor species of the setting.
With most species recovering in a mere 35,000 years the galaxy has been largely left alone by its neighbours. However with the discovery of Killaryte, a extremely rare mineral, has spurred an already exiting colonisation programme between the Transgalactic Empire, the Consortium of Civilized Worlds, the Splugorth Kingdom of Desslyth, and other assorted factions, including the thoroughly unimaginative medieval-Japanese style Bushi Federation largely inhabited by the "Oni". This setting of interstellar imperialism comes with a collection of exotic treasures from the previous species that used to inhabit the lightly populated galaxy, although such treasures are far from what could reasonably call 'alien'. Of more significant interest are the anti-technological Denlech, a human cult that has almost entirely renounced technology due to some bad experiences, but often come with some special natural abilities.
Then we have a large collection of what are meant to be aliens. In reality, most are variations on humanoids, such as a humanoid tiger, a humanoid with a carapace and scorpion tail, a bug-eyed humanoid with long limbs and fingers, a humanoid with mottled skin and horns, and so it goes on. Somewhat more interesting are the Shakdan, a sort of bug-eyed floating giant slug with multi-fingered "hands", and a hive mind, and the Whetu, a six-limbed, triple jointed species with large chest-positioned mouths, and particularly good vision. The robotic Pyashche Probe, also deserves an honourable mention for being at least somewhat reasonable as an distant alien contact and observation vessel. On the very silly scale of things is the Abatwa, semi-naked faeries who, at least according to the graphic, ride rats like horses, and a lightning-summoning, hammer-headed duck.
There is little to be said for the random generation tables for other odd monstrosities, or colonies, except for the point that something like this was always going to be a necessity if you're going to try to describe a galaxy. Of more significant note is the collection of one hundred adventure and one seeds to conclude the text. Sure, these sketches are a mere paragraph long each, but there is hopefully something there to provide a spark for an ideas-strapped GM.
If this review seems short, it is because the text is so short of content that is even vaguely interesting. Thundercloud Galaxy is simply not recommended. Theodore Sturgeon once remarked that ninety percent of science fiction is crud, just as ninety percent of all contemporary artforms are of this same quality. However this is a particularly impressive example of a work of utterly juvenile imagination. Maybe an idea or two can be rescued from it; but ready it is a pretty hefty price in time for such limited resources.
Style: 1 + .4 (layout) + .4 (art) + .0 (coolness) + .4 (readability) + .6 (product) = 2.8
Substance: 1 + .1 (content) + .3 (text) + .0 (fun) + .0 (workmanship) + .2 (system) = 1.6