There is a certain meme going around in the internet RPG circles, in which one asks "But what do the PCs do in this game?", then deriding any attempt to answer with "Well, what do you want to do?". I think it's pernicious, because only a focused game has a narrow enough sphere of play to answer anything else. I have no problem with focused games! Some of my games are very focused - if someone asks "What to the PCs do in In Harm's Way: Aces And Angels?" I can answer "They play WWII fighter pilots." Totally cool. But when someone asks "What do the PCs do in StarCluster 3?" I can't bang out a simple answer.
In focused games, the designer intentionally limits the scope of the game to a small area. Why? Because of the magnification principle - Given the same quantity of data, field of view is inversely proportional to visible detail. In order to achieve a highly detailed view, one must limit the field of that view. In order to see a larger scope, detail must be lost. Thus focused games are those where the designer is interested in detail rather than scope. Non-focused games are those where the designer was more interested in scope than in detail.
There are two ways to get more detail in a non-focused game - increase the data/bandwidth or delegate sub-creation. If you make the game bigger, you can get in more detail. The larger the quantity of available data, the more detail can be fit into a given field of view. By delegating sub-creation. the designer encourages the Group to provide it's own focus. This allows the group to provide its own detail by arbitrarily focusing on some aspect of the game which the group chooses to explore in more depth.
This also brings in the two somewhat contradictory definitions of a game - Game As Written, the book or pdf the designer supplies, and Game As Played, what actually happens in your group. In a game of extremely wide scope and delegated sub-creation, the Game As Written can be essentially unplayable - and this can be a good thing! The group must transform the Game As Written into the Game as Played by sub-creation. If the framework of the game is solid and the process explained well, and especially if tools are provided to help the process, then one should end up with a custom game, produced especially for your group, taking into mind what the group is interested in doing.
So Games As Played are all essentially focused - the only difference is who is doing the focusing.