Some great responses were posted, but no one really mined the vein I was thinking, because I wasn't very specific.
How much leeway or freedom do your players have in the sandbox?
I have recently decided to think of sandboxes as varying in size. Here is a rough breakdown:
- Infinite breadth of options
- In this type of sandbox, players are given a literal "anything goes" card. The DM either has invested a ton of time in preparation, or is (like me) relying on his ability to build on the fly.
- Players are not given any scenario or issue to consider. They are merely placed in a world, given descriptions of that world, and asked "What do you do?"
- There is no starting point or ending point for adventures in this type of world.
- Limited breadth of options
- While the DM may have a world planned (or created on the fly) that can accommodate the "infinite options" type of game, for some reason he or she has chosen to limit the PCs in some way.
- Examples of this include my recent Savage SciFi game-- I created a world, gave the PCs vast input in its creation, but set up a specific starting scenario. No goals were laid out by me, but there were a few more obvious possible outcomes of the initial scenario. Because I gave the players full freedom at every turn, though, they surprised me at every game session.
- There is a definite starting point for adventures in this world, which naturally precludes some options, but can help set up a particular style of adventure. No end point is laid out.
- Railroad with options
- I think of this as analogous to most RPG video games, like Final Fantasy. While there is freedom to explore the world, level up, pursue side quests, the DM still has a definite "win scenario" in mind (or maybe two or three scenarios.)
- I hesitate to use the term railroad for this type because it is still not a set in stone type of plot. It is probably much more flexible than the stereotypical railroad.
- You can think of this type of sandbox as having a line laid in it, showing a start AND end point.
- Railroad (aka Not a Sandbox)
- Do I really need to define this one?