Tonight, my buddies and I are going to embark on a new game that I'm GMing. We're playing Fading Suns with the Spirit of the Century Rules (instead of that crappy victory point system or D20). I've played in a 6 month campaign of Fading Suns before, and I love the setting. It's Middle Ages in space, with a touch of Roman Empire thrown in, and a huge array of different planets and campaign possibilities. The setting is also politically explosive, and it's explicitly aimed at having large scale political repercussions for PC actions. With source books galore, it's maybe one of the most well supported settings I've ever seen. But there's a potential problem that I've quickly run into: With so much source material and options for players, it can be demanding on the GM.
Contrast this sort of game with the sandboxy old school games that are all the rage right now. I'm actively playing in one of those right now (using the Savage Worlds system), and I'm really digging on it. We can go wherever we want, and every little thing is a struggle. We've been playing for about a year, and we still had some serious problems with well positioned goblins not so long ago. The map is set, and the GM doesn't force any plot hooks on us. I know this took a whole lot of preparation on the front end to get this sandbox up and running. But in game, things seem to be more straightforward for the GM.
On the other hand, part of the appeal of Fading Suns is that players can move from world to world, and city to city on these worlds. As a GM, I have some plot hooks for players, and Spirit of the Century is set up to give players incentives for characters to follow the GM's lead (there's a really cool mechanic for this, called invoking aspects). Some degree of player buy in to what the GM has planned is necessary for this sort of game. But the last thing I want to do is railroad the players. After all, I get most of my fun from GMing from trying to flexibly respond to the unpredictable things players do. On a very large scale.
In fact, the large scale nature of the game is what appeals to me so much. It's just how my mind tends to work. It's what fascinates me. But it sure makes for tough preparation and on the spot GMing sometimes. As we play, I'll keep posting.