This is starting to feel like banging one's head against a wall. That is exactly what is going on in people sandboxes.
Not in the ones I've seen? Maybe I wasn't quite clear with what I meant:
- In most FITD games, you have a strong core premise of the game itself, what the macro "playing to find out" is (we're here to explore the success or failure of new criminal gangs in a victorian city filled with ghosts / we're here to see if Magical Girls can face the trouble of their emotions and the pressures put on them from their opposition / we're here to see if we can bring a disparate revolutionary coalition together to take down the Vampire overlords / etc).
- You generally have a secondary Playset / Crew / whatever, that has specific sub-goals and frames teh fiction (we're Hawkers, selling illicit substances; we're mecha pilots struggling against extinction; we're facing off agains the Vampire Lord X an embodiment of Y tropes about the real modern world).
These two alone start directing the overall thrust of play, before you even truly begin in a way that I think "we pick a spot on the map" doesnt quite do; you've already flagged to the GM what a huge amount of play is going to involve. From there, the players can pick directions they want to go to pursue the interests of their overarching umbrella - how do they want to find new turf to sell their drugs; where and how will they battle the leviathans; what faction do they want to try and bring into the revolution or where do they want to challenge the Vampire Lord's hold.
Once you've got that, you make an Engagement roll (or equivalent) and you're in the action; no intermediate space.
A good chunk of this thread has been people stridently saying that even though there's some core "sandbox-equivalent" to stuff like Blades I'm assured it doesnt look like "actual sandbox play" at all because the creative priorities are different due to everything above.