Thanks. My big issue was in X-COM you can use sensible tactics like sweeping the map slowly, with cleared areas entrances being watched so aliens don’t move back into them.
The other thing I learned about X-COM (2016) vs X-COM (199X) is that in the old ones all aliens on the map are active, if you can see them or not. So in some maps (Terror missions) it makes sense to move around and rush as civilians are getting killed and turned into aliens. However, in the modern one, encounters don’t activate until you see them, so you should keep your forces bunched up, so you only see one encounter at a time.