My thoughts on this are that its best to learn a programming language and process a turns counter in which if the number of turns reaches certain intervals you can trigger other events to happen in the game. You could even have an Easy, Normal, and Hard Mode in which the easy mode gives more turns before events trigger that are likely events that are bad that you have to fend off a problem etc, and normal mode having fewer turns than easy for the initial construction period, and hard mode being even fewer turns in which you really need to know what to make in what order to be able to sustain against the attack etc.
Curious as to this games visual construction.... in batch etc?
Are you happy with it being an ASCII based character constructed game or will you be creating a real graphics generated game which can be done in a number of many languages out there such as C or C++ or even simpler to call bit maps from within the code vs constructing each pixel placement etc?
I'd suggest not doing this in batch unless you are doing this as a fun way to strengthen your skills in batch, however the limitations of batch may be frustrating.
I have made games before in batch and hit walls that otherwise wouldnt have happened in creating the game within a true IDE such as C or C++.
If you are working with a DOS system even QBasic offers much more than Batch alone. Also the cool thing about QBasic is that if you know the older line number Basic programming you can code in QBasic in a legacy format of what normally would have been in GW-Basic format and the games will run. However if wanting to make a modern like game, I'd suggest C++.
If you are not good at creating graphics, another method of making turn based games is to make the game with HTML and a Scripting language such as Java Script, in which the Javascript handles the logic and the browser is used to display HTML web pages with text and pictures, in which you can create or use already created pictures called thru the javascript to display. Many Many turn based online games have this same layout of dynamic text and images that are called to fill the browser window, however they go beyond JavaScript which is ( Local ) logic and the logic instead is server side of the web server serving up the dynamic web page to the many connected players with player accounts.
For the fact that you seem to be part way through a project I am eagerly awaiting your construction methods and execution of this game that you are making.