I want different things to happen at different times in my game, but I'm stuck on what "sort" of time that should be. Okay, let me explain more clearly:

For example, there is a huge tent/marque in my game. At certain times I want it to be full of people, other times it's empty. But those are set time periods.

So, do I go for:

1/ "Real time" - a clock starts at the beginning of the game and after X number of minutes then the tent is empty?

2/ "Turn-based time" - when the number of turns gets to X then time moves on and the tent is empty

3/ "Completion of certain tasks" - after the player has completed specific tasks then time moves on and the tent is empty.

All three have their positives and negatives, depending on how long the player takes to go through the adventure.

What do you think?

I've implemented a few escape room games that should take about an hour to complete. They measure real time and allow the player to suspend the game to pause the clock.
The games are:
https://textadventures.co.uk/games/view/n_zp37nys0cr1mgfoto65q/ten-pin-panic
https://textadventures.co.uk/games/view/jqt79vk0hkiy20jborspoa/trapped-in-tomorrow-today
https://textadventures.co.uk/games/view/3lgxoq8rv0mcsakciuqj6g/now-you-see-me
There is no cut-off time. It's just for entertainment! I personally don't like playing against the clock.

I used #2 in my House on Haunted Hill...
I played a snow survival game that used a real time clock...
If you read slow, or type slow, you would die every time.

A thought... The tent will not go from empty to full in one turn...
Each turn, a few people will enter and a few less will leave.
And the same as it empties...
It just maters on how accurate you want it to be.

"A thought... The tent will not go from empty to full in one turn...
Each turn, a few people will enter and a few less will leave."

Thanks for the replies.

With regards the tent filling and emptying, there are events held within the tent at certain times, and when they are on it's "full of people sitting at the tables and on the benches or milling around" then other times "the tables and benches are empty. It seems eerily quiet considering how noisy it is at other times."

I don't want to start getting into "a few people enter or leave" situation.

I had a timer that counted seconds into the game and added an hour for every major task fulfilled. That way time never stands still and time goes by in a realistic and meaningful way when you play, as well.

True, adding few every turn would be a mess...
And during "events" it would fill and empty quickly.