A THREAD FOR NEWCOMERS!

Thank you, now a new question: is it possible to set a temporary barrier (for example, so that a hero can use a portal only after 15 game days, and before that, he cannot use it or even approach it)?

You can create a passage guard that requires a specific quest, but the player will only be able to complete this quest on the 15th day. For example, he has no way to obtain a certain resource (e.g., 1000 units), but after 15 days, an event timer will give him the required amount, and he can exchange it for the ability to pass.
Or, a second option, if the castle is fixed, you can require 1 creature that will not be available for construction, and on the 15th day, this building will appear in the city (the main thing is to exclude any other possibility of the appearance of creatures of this type), the player buys the creature and exchanges it for the right to pass.