how can you tell when 24 hrs passes??

I think you can look at your clock. If you don't have a clock...just wait a day and try again.

I think the 24 hours is human time...not necessarily game time.

Good luck!

It's on your clock!! I'm pretty sure that it's question of 24 hours of our time!!

If you're talking about the chief doing something, it is a literal 24 hours. Pause the game and open it tommorrow and the 24 hours will passed.
If it's a time until puzzle completion kind of thing, that depends on what speed you have it on, but the thing you clicked on to get that 'time' will have a countdown.

Marcey