This book has no business being as good as it is. It actually kind of upsets me, because the only reason I bought the Trinity Continuum Core Rulebook was because I was interested in Aberrant and (to a lesser extent) Aeon. I'm afraid that's going to be the book's predominant reception - it's the thing you have to get in order to play the other Trinity Continuum games. But viewing it that way would be a mistake. I think you could credibly make the argument that core-only Trinity Continuum is actually better than playing in any one of the marquee time periods (and yes, I'm including Adventure!). At the very least, it's a strong contender for the best core book White Wolf/Onyx Path ever made.
What about it has earned it such effusive praise? There are three factors.
The first is that it stakes out an under-served niche and then sells it very effectively. I'm finding myself at a bit of a loss to articulate what exactly that niche is, but if you read the book, you'll get a very clear idea of what it's going for. I guess the best way to describe it is like, those movies and tv shows that are ostensibly set in the real world, on or near the present day, that don't seem like they have a lot of magic and/or sci-fi technology, but then there's an episode of Mythbusters or a Youtube video that proves conclusively that duplicating it in reality is highly implausible at best and extremely dangerous at worst.
I'm sure there are other games that tackle this "Hollywood reality" aesthetic even more directly, with various narrative mechanics, but the Trinity Continuum Core has the advantage of doing it while still being a relatively traditional rpg. It does this through the second great thing about the book - Talents.
Talents are the obligatory superhuman archetype found in every storyteller-family game. You start as a normal person and then you apply the template and become a Talent. In the broader Trinity continuum, Talents have an important role in the metaphysics. They can instinctively sense and manipulate Flux energy, mixing and fusing nearby parallel realities to accomplish superhuman feats of luck and skill. Practically, this manifests in "powers" that are nothing more or less than the ability to apply to your character a variety of genre cliches and lazy screenwriting shortcuts.
Maybe you're in a gunfight, and you lose count of your ammo, so you just keep firing and nobody ever notices that you never reload - that's a Gift. Or you're a private detective, and no matter where you travel, you always "just happen" to have a friend who will let you crash on their couch - that's a Gift. That's how Gifts work. Taken as a set, they make your character feel like they were written by someone who's not too big on sweating the details.
That's the best way to use Talents. Set aside the continuum technobabble explanation and just lean into the idea that their Gifts are narrative-level permissions you have as a player to make your character's life easier. Don't even acknowledge that they're anything but normal (albeit highly skilled) people.
This isn't entirely a hack. There's a sidebar that acknowledges the possibility. It's pretty perfunctory, and I wish that the subject was given the full "alternate campaign model" treatment in the storyteller chapter, but you're not out on a limb if you use Talents to stand-in for "has protagonist powers."
It's hard to overstate how strong the book is if used that way - Talents are the default character type, their Gifts just meta storytelling flags. It all ties back in to the genre stuff I was talking about. You can use this book to play Die Hard, to play an Ocean's Eleven-type crew of criminals, to emulate shows like Person of Interest and Sherlock. That's what it's for.
I can't say with certainty that something like Fate's Aspects or Chuubo's Quests wouldn't work better for establishing that slightly-heightened/slightly-crummy reality of modern day action and procedural dramas, but I do know that the Trinity Continuum Core manages to do what it does while still being, like, 90% of a regular rpg. You wanna play Fate, you're going to have to tell your players to unlearn much of what they've learned playing D&D. Gifts, by contrast, take about a second to explain. "They're spells that look like luck."
This discussion of genre brings us to the third and final thing that makes this book a tragically hidden gem - it's a complete rpg. Now, on some level, this is just my passive-aggressive swipe at Scion: Origin. That book was ostensibly a stand-alone volume, but it nonetheless conveyed a certain incompleteness. Your character options were defined by your relationship to gods who would not be detailed until Hero, your abilities were capped by traits that could not be raised without the rules in the later volume. Origin has a great high concept, but it didn't fully commit.
The Trinity Continuum Core commits. It gives its characters, both normals and Talents, plenty of ways to branch out and grow in power. It provides all the rules you're likely to interact with along with a framework to expand the setting without access to the other Continuum era books. There's nothing here that feels like it's being held back to punch up a future release. And because of that, I truly do believe that the Trinity Continuum modern era has every bit as much ability to support a full line of supplements as any of the flashier legacy settings.
A shame then, that it probably won't happen because the knee-jerk reaction is to dismiss this book as a means to an end, the thing you need to play Aberrant. If it could get past that reaction, it may well come in time to be viewed as one of the great one-volume rpg books, alongside the likes of Unknown Armies, 2nd Edition or Star Wars Saga Edition.
Ukss Contribution: I'm going to go with Les Fantômes, the notorious group of high-society thieves with a code. They steal exclusively from the ultra-rich, don't harm innocents, and sometimes indulge in a bit of justice on the side. They could anchor a whole series by themselves, either as antagonists or anti-heroes, and pretty much have a place in any setting where capitalism might run amuck.