I have a simple combat system where unit have an initiative order of attack, then roll a die and have the potential to kill or rout enemy units which could then be killed if routed again. Artillery shoot first, then infantry then cavalry.
Now, the problem is that since it's a solitaire game, I do not want to handle retreats, because it will bee too annoying for the AI to retreat. So I was thinking of continuing battles until one side lose all it's units.
But since each unit could kill at most 1 unit, unless you have numeric superiority, you will never kill all opposing units. So multiple battle rounds are necessary.
But it seems a bit illogical that after the cavalry has attacked, that it goes back to artillery again. The thematic reason that artillery shoot first is that their get their first shot while the enemy is approaching.
The only logical reason is that there could be multiple assaults. Doing another round of combat is another assault on another day. It could also give you a chance to recover routed units between assaults.
Else I would have to make killing units faster, and possibly remove routing, but it would reduce the depth of combat.
Considering I am going to have a lot of unit type others than the basic 3, I cannot give additional special conditions, that would just multiply the rules.
Victory II simply roll all units at once ( 1 die per unit type), but there are still special abilities that happens in a special order like artillery, but I think it only happens once, then you roll indefinitely.
By "Ruin Wars", I imagine you mean "Rune Wars". Still a game called "Ruin Wars" that takes place in a post apocalyptic world could be cool. Since I did not want to handle retreat, this is unfortunately not an option.
I think the multiple assault (different days of battle) with option to regroup each round would be the solution.