How long is Tyranny?

[TinyWiking]

Huge.
No, seriously, how do you mean "big"? The size of the installation or the length of the game? If it's the later it will probably taken 20-25-ish hours to complete.

 

[TinyWiking]

You can finish it in 20-25 but there will be things to do that extends this, plus, depending on several choices you make in the beginning the game will play very differently with each play through. For example if you pick A in the beginning city F will be destroyed but pick B instead and city F will be a alive and well but something else changes.