We have to decide what to do with range variation, as there is no physical positioning for units, and as we have only one range for the entire forces in presence. In reality, forces would be at different ranges from one another, to the point, if you get very detailed, that you are back to having positioned on a grid the various forces (aka a tactical module!).
So you have one range. On the first round, the range start at the highest distance possible and goes down to 0. There are several sub-rounds, where each element fire as soon as it reaches its maximal range. It is thus interesting to fire farther than the other.
Then each round is made of 2 subrounds, range 1 and range 0.
Hofstadter's Law: "It always takes longer than you expect, even when you take into account Hofstadter's law."