How hard is it to make a army formation that travels in formation to where you click with your mouse. Also being able to select individual soldiers and move them. Is this too hard? Or is it simple?
That depends on what your formation is.
If it’s something like a square (rectangle) or a circle, then it wouldn’t be too hard, because you can extrapolate individual position from the shape with simple math. Same thing for a straight line.
More complicated shapes like maybe a semi-circle, or a /\ arrow formation, may take some extra work, but they shouldn’t be totally unreasonable for anyone to make.
Same thing if you want the shape filled with troops. Simple shapes would take simple math, just more of it.