[RPG] Problems to look out for if you are a D&D group who play Fate for the first time

First off, DFRPG is full of "the group should agree" (YS92), "keep in mind the intended play style" (YS31), "make sure your players are okay this" (YS338), "make sure you're on the same page as your players" (341), and "when in doubt, talk it through with your group" (YS99).

In many places throughout this book, the phrase “the GM decides” is often used interchangeably with “the group decides” regarding some of these issues, because it emphatically isn’t the GM’s job to run a dictatorship—every player should always be allowed the chance to have a say in those instances. The GM should act as more of a moderator, synthesizing the group’s input with her own in order to reach a final decision. [YS306]

But I'm going to focus on the Lawbreaker thing, because that's a lot more quotable, rather than an obvious system philosophy.

Concessions

A concession has to pass muster with the group before it is accepted [YS 206]

This is framed in the context of a concession not being too lenient; it must "represent a clear and decisive disadvantage for your character." However, I see no reason that an extra-harsh concession (like death) should be able to bypass the group approval requirement.

Lawbreaker

The section on the Laws of Magic discusses them in terms of choice:

Whenever you choose to break one of the Laws of Magic, you’re crossing a very real line. [YS232]

Once a character has chosen to cross the line and break a Law of Magic, that decision is a part of him however you look at it. [YS233]

But then the section on the First Law says,

This is one of the easiest laws to break by accident [....] Accidental deaths can happen, and in those cases killing with magic still counts as killing when it comes to the Lawbreaker stunt. [YS235]

This seems to be an invitation to the GM to orchestrate accidents, but it's not: it's a statement of in-world assumptions, not the game's philosophy. I can say this with certainty because the very same section immediately says,

Your group should discuss how important they want the First Law to be in play. [YS236] Ultimately, the GM needs to be careful and conscious about putting life-and-death human adversaries in front of the players. [YS236]

And makes very clear that this isn't about creating a bunch of outlaws, but about

[...] giving the First Law a strong and palpable presence in the game. A number of players might enjoy this as well, welcoming compels directed at, say, their Wizard of the White Council aspects to remind them that the First Law is an obstacle to their actions when a life is on the line. [YS236]

So that seems pretty clear: both concessions and the breaking of laws are in the hands of the group as a whole rather than the GM exclusively, and interesting narrative is at the fore of the game philosophy. To make it absolutely beyond doubt, I'll finish with this:

Who determines that a character has crossed the line? This is something that a gaming group should decide on as a policy for their specific game. [YS234]

Now there are two sides to that coin.

The good part is that Fate is an awesome system when it comes to player-vs-player games. Sometimes the narrative leads to a situation when two player characters find themselves in the opposite sides of the fence. The typical fate mechanisms like invoking and compelling, coupled with the fate point economy, lends itself to a self balancing game where the players take the lead in creating a story and doing the usual GM job of creating the conflict all by themselves. In a game where the players have internalized how Fate works, all you have to do as a GM is sit back and enjoy the show, and occasionally throw in a wrench by playing the rest of the world just as a player plays his character.

The bad part is that because the Fate system is a narration system as opposed to a simulation system, in which some points are deliberately left open to discussion and consensus on purpose, it is easily exploitable by powergamers who see freely bendable opportunities everywhere.

I have played a lot of games that turned PvP using Fate, and whenever there was a powergamer in the group that attempted to dominate the game, I used this three level approach to get things going smoothly.

1. Indulge the powergamer's desires by letting him become the antagonist, letting the story flow into that state in a regulated pace.
2. If the powergamer is pushing too hard, question him, ask him how he does what he does without trying to shoehorn it into the game mechanics. Call BS on him unless he comes up with an awesome story that everybody enjoys even if it is to their characters' detriment.
3. If the powergamer becomes abusive, create a situation in which he cannot accept failure, and push hard to drain his Fate point hoard. He will effectively be neutered for a while and hopefully find some time to reflect.

And of course, if he insists on ruining the fun by other means, kick him out as usual. Fortunately, I never had to come to that with Fate. My regular powergamer had a taste of the third level for a couple of times, getting brutally killed by another player's character in one of them. He has now learned to enjoy the game at the first level and provides formidable opposition for other players.