This is what I have come up with for my upcoming AAR (2nd Legion, Eagles of the Republic). It is designed to be entirely historical (as close as we can come with the RTW engine). Tell me what you think and feel free to add more.

Quote Originally Posted by The Rules
All armies must be led by a general. If their general is killed, then they must either stay in the rough location they are in a defensive manner, or return as directly as possible to a general. The priority for Generals getting command depends on their position in the Cursus Honorum. That is:
1 – Consuls and Proconsuls (Censors will also fit into this category as Proconsuls)
2 – Praetors and Propraetors
If I do not have enough of the above to fill up all available commands, then the remaining order is:
3 – Aediles
4 – Quaestors (Usually on appointment to a province)
5 – Military Tribunes (Can take over command if the general is killed on campaign)

During the Camillian and Polybian eras I shall have no more than 4 legions. Yes, this will be incredibly difficult, but I am trying to make this as historic as possible. All legions are comprised of 10 units. The list of units is shown here:
https://forums.totalwar.org/vb/showthread.php?t=79935
Consuls and Proconsuls are allowed to command 2 legions. In addition, Praetors and Propraetors can be granted Proconsular Imperium, allowing them to command 2 legions as if they were a Consul.

16 years after a legion is completely recruited (Which can in fact take up an entire year if I am strapped for cash), it must be disbanded. In times of national or regional emergencies (For example, when about to engage a full army while in a province or on campaign), this can be expanded a further 4 years. This legion will be disbanded either in new provinces, or back in Italy.

To balance out the 16 years of service I am allowed to retrain units, however I am not allowed to recruit units that will then be combined with my other ones. This means that in order to get fresh men, I either have to start relying on local soldiers, or return to Rome. This is historical. Note that if a unit is completely destroyed (And I have had it happen using these rules in the last AAR) then I am allowed to recruit a unit to replace it and send it directly to a legion.

At the end of winter, all armies must either be in a fort, or laying siege to an enemy settlement. This is to represent the increased difficulties that armies often had during winter if they were unable to find shelter from the cold. It was a standard thing for commanders to encamp their armies during winter.

I will attempt to role play the characters as much as possible. The concentration will not be on them, they will simply be side characters to the main hero of the story. For those who don’t know, Third Legion followed the story of a single individual who was a part of a unit. In this case, the commanders were often side characters who were merely commented on from a specific point of view.

All cities and provinces should have a Governor at all times if one is available. Rome will hopefully have a Quaestor governing it. Further Quaestors will be assigned as Legatees to any Provincial commanders.