I'm really surprised that Unknown Armies has not received the attention and affection it is due. It's a really, really good rule set. It wears its Call of Cthulhu heritage on its sleeve, but manages to innovate in a few key areas. As for the setting, it's fast and loose and has the sense of humor that the World of Darkness wishes it had.
Here are a few things that I specifically love about Unknown Armies:
Free-Form Skills. There are a handful of default skills that all characters possess, representing the common knowledge for modern adventurers. There is no skill list beyond that. Characters can be skilled in "comic book trivia," VCR repair" or "drop dead gorgeous," or anything else the player can dream up. I especially like this because it gives players an excellent handle on what their character can and can't do, which sometimes isn't the case in games with classes or restrictive skill lists.
Fate-Like Aspects Without the Foggy Rules. Each character has something that makes them mad, something that makes them afraid and something that makes them noble. These "passions" work much like aspects in Fate, but with some easy to follow rules that make them easier to comprehend for new players. They are balanced abilities that help fill in the character without expecting the player to come up with a detailed backstory on the spot.
Only Roll When Shit is Hitting the Fan. I've heard GUMSHOE is great in that it doesn't allow for players to miss key information or story points because they missed a roll on what would have been a simple task for their character. Unknown Armies takes the same approach. Any character with a 15% or more in a skill will automatically succeed a task using that skill provided they are not under the gun. And by this I mean literally being shot at. Challenge maintenance has always been tricky for me as a GM, so I welcome this philosophy of keeping the dice still until things are especially difficult.
Four Sanity Tracks. Everyone loves going insane in RPGs. Unknown Armies brings more fun to the table by allowing a character to become crazy (or callused) due to exposure to four different kinds of stress: Violence, the Unnatural, Helplessness, and Self. The Self sanity track is an especially helpful check against players who have their players turn into sociopaths when it is advantageous.
The Setting is Basically the Illuminatus! Trilogy. A million different gonzo conspiracies are operating at once, somehow slowly pushing the world to the brink. McDonald's has been infiltrated by free-wheeling occult hippies. There is a goddess in the form of a porn star. Every conspiracy theory is real. Every myth is true. Robert Anton Wilson would be proud.
Schools of Magic Are Not Political Groups. One of the biggest flaws in the World of Darkness games, especially Mage, is how the various schools of magic seem to be separate political faction. It seemed unlikely that any member of one school of magic would ever work with a member of another school considering how much each school is supposed to inform the worldview of the character. Unknown Armies doesn't have this problem. The magic schools are colorful and varied but there are very few social restrictions imposed upon the characters. This makes mixing and matching magic schools within a group fun and exciting rather than an exercise in rationalizing.
