Global Hide and Seek
Should you do this? No. Will it work? Probably not. Is someone going to try anyway? Almost certainly. So here are a few thoughts on how Hide and Seek could work across the entire globe.
Firstly, you almost certainly won't be able to dictate a specific list of transit networks that are included in your game, so you'll have to set a general set of parameters for valid transit stations instead. For example, this might include "commercial airports that serve at least 100,000 passengers annually," and "non-metro train stations."
Secondly, the basic time scale we've provided for large games would not work here. You would need to use a new global time scale. Hiding periods would last 24 hours. Scalable time bonuses, time penalties, and time limits would follow large-scale values multiplied by 5.
Many–or most–curses would need to be removed and replaced. Curses that aim to slow seekers down by distracting them with an activity–such as Curse of the Cairn–would be essentially useless at this scale. You would almost certainly want to write new curses that correspond with the amount of time and money being spent in this version of the game. Perhaps a curse that sends the seekers scuba diving for a particular kind of shell? A curse that forces them to climb a mountain of a certain height? A curse that forces them to camp on a deserted island?
You'll also need to add more questions, in almost every category. Add hemisphere, continent, and country to matching; add the equator and national capital to measuring; add much larger radars; additional thermometers; probably a whole new larger category of tentacles. All kinds of stuff.
Anyway, there's almost no way that this game could be properly balanced. Don't do it. Spend your money on something sensible. Put it in a mutual fund or something. Please don't do this. (But if you do, let us know. We're just the tiniest bit interested in what might happen.)