These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Broken Base: Between the Fandom, the constant calls it was ruined following anynew Sourcebook, rules change, the rules not changing for decades, or Canon Defilement (perceived or real)...and the occasional (rare) rational disagreement over an issue related to the game or setting...the Rifts fanbase has split more times than a sequoia's root system.
Feeling cold? Hop on over to rpg.net and post anything about Palladium games. The ensuing flame wars will heat your home for months.
The Palladium forums, though, are pretty tame, partly due to strict moderation. (The Fanwork Ban, one of the bigger sources of flamethrower fuel elsewhere, is fully supported and obeyed here.)
Draco in Leather Pants: For all the atrocities they commit, the Coalition can be surprisingly easy to sympathize with. After all, the vast majority of the world's problems actually are caused by magic and/or creatures from other dimensions. If it weren't for their zero tolerance policies and ceaseless propaganda, they would easily come off as The Federation.
This gets brought up in the introduction to the second book in the Siege on Tolkeen series. Siembieda states flat out that "die-hard fans of the Coalition" will probably be displeased with the way the CS is portrayed in this book. But nothing in the book is coming out of nowhere, it all fits previously-established techniques and doctrines used by the CS for decades now.
They probably wouldn't get hit with this trope so hard if their armor and weaponry didn't look so darn Badass.
On at least two occasions CS troopers have saved the life of Erin Tarn (admittedly not knowing who she was other than an old human lady) from monstrous threats. It is actually possible for CS characters to be Lawful Good, because so much of the world around them is filled with evil monsters, while they themselves are deliberately undereducated and ignorant of politics. Thus they do not know enough to realize their government is evil until it really gets rubbed in their faces.
Game Breaker: If the character you are playing doesn't break the game in some way, shape, or form, you're doing it wrong. Oddly, although they're really just a Mighty Glacier class writ very large, the Glitter Boys get all the heat for this trope.
The Cosmo Knight, however, is simply ridiculous.
And the Godling makes the Cosmo-Knight look sane.
And the Elder Magelord makes the Godling look like a wimp. First session with one of these, I tore apart a Glitter Boy with my bare hands.
Misaimed Fandom: The Coalition States provokes arguments about this: some hold they cannot possibly be good, others note that integration is effectively impossible so they just might be what they claim.
Or just being an ordinary human that the CS has no immediate need for. The Burbs are populated by people who have been waiting for generations to gain CS citizenship, and it is not because the CS bureaucracy is slow.
This issue can often be resolved by simply turning to Word of God. Kevin Siembeda admits that while some CS characters may be sympathetic, his overall depiction of them as being predominantly evil is pure Canon. Multiple books contain examples of the CS being extremely malevolent, including orchestrating the deaths of humans purely to create raw footage for propaganda purposes. Also, players whose characters are actually forced to obey CS laws and military regulations often lose their enthusiasm for it quickly, since freedom and independent initiative are strongly frowned upon in the rigidly hierarchical military government, which is not above punishing (or killing) Military Mavericks who might shake up the status quo.
There's some stuff, like the Soul Harvesters (guess what they do) from Psyscape, which is so disturbing that the book has a disclaimer right before that section warning off folks with timid sensibilities.
The artwork and concepts of the four Horsemen of the Apocalypse in the Africa world book.
The mutants in Madhaven. Their freaky appearance is bad enough until you remember that they're all descended from humans.
Before their divorce, Kevin's wife Maryanne was usually listed as the editor. One wonders if she did anything beyond typesetting and posing for various pictures.
Purity Sue: The Perola. Pacifistic, well-loved, attractive, charismatic.
Strawman Has a Point: the Coalition States is portrayed as a nazi-esque pro-tech anti-magic big bad who are racist against aliens/psychics/mages. Their views are promoted as being irrationally paranoid and intolerant. Actually examining the powers and abilities of something like a dragon or a high-powered psychic makes them sound a lot more sane. People who have played a lot of Rifts tend to slowly drift towards the Coalition's viewpoint that the possession of certain powersets makes you a constant threat to everyone around you, and you should be treated as such.
Exposure to a Nonhuman Tactical Strike/Elimination Team campaign aka Supernatural SWAT, which is basically a crash course in just how bad things can get in this department, tends to radically alter the views of players about how much of the Coalition is crazy.
Word of God: System creator Kevin Siembeda enjoys his ability to state what is and isn't canon. He isn't like a lot of other RPG authors who suggest the GM should do whatever they please: the books contain notes and pointers on what to do as footnotes.