The term "free to play" has some pretty negative connotations. Casual and mobile games have certainly made the concept painful and expensive. Often, "free to play" games require large sums of money to actually play them, despite their name. That is why the decision to make new Fable free to play on Xbox One and PC initially sounds devastating to fans of the series. They have promised 3 tenants for the game.
The good news is, this is not the same kind of free to play. In fact, you will have free access to the entire game, not just small sections of the game, with paid locks on others. This is their first promise to players. Users will be able to earn silver in the game, giving the ability to purchase goods inside of the game. There will, of course, be paid items in the game, but nothing of consequence. These paid items will include things like cosmetic items, etc.
In addition to an open game, the company promises that the game will also be fair. This means that anything that is required to continue playing the game will be available in-game. This means that no portion of the game will require a purchase to advance, distancing itself from the normal "free to play" fare.
Finally, the company promises to be generous in the game. Mostly, the goal here is to make a game and a scenario that encourages a happy player community. The success of a game like this revolves entirely around the happiness of its players. Unfortunately, that is not always a goal of the development team for a game; if it was, gaming would be a significantly more entertaining place.