@Caesar: Well I could probably start on a list of the Roman provinces and try to figure out which counties would be de jure part of it so you could basically mod them as seperate titles into the game. You could add a decision of "restore Romand beaurocracy" for a high gold (to establish new offices) and prestige costs that would also need to be unlocked as a culture specific innovation only available to the Romans. That decision would destroy the existing Duchies and Kingdoms within your empire and replace them with provincial titles (only creatable for characters of Roman culture and holding one of the Roman empire titles). However those titles would need to be non-inheritable. You could tie the revocation without tyranny to a cultural innovation in the high or late medieval innovation tree. Once you have researched Provincial systems you could then create those titles once you completely control the de jure territory. It would also help if this innovation would remove the feudal vassal limit given that it makes no sense in that context since the point of the Roman beaurocracy innovation would be to administer a vast empire through basically civil servants.

So you basically would have two main obstacles for the player: You need to discover the cultural technology needed, you need a vast amount of money and prestige to reestablish the civil service. Proportionally the cost of creating a new province title should be higher as well. However, counties that are not part of the provincial system (so not part of any Province title) should count against your vassal limit and should get a massive tax hit for not being part of the pax Romana to show the importance of not just conquering territory but actually introducing Roman law to the provinces. That should slow down the steam rolling as I would suggest the counties would need to be of Roman culture before you can create a Province title. I know that would be a massive undertaking modding wise, but it would really add some flavour and set Rome apart from other titles. It's a bit similar to the Byzantine mod I mentioned however I don't think he takes it far enough since he basically has the same titles and just renames them, the vassal limit still applies so in the end you end up with 50 small kingdoms instead of 10 big provinces split into 5-7 smaller provincial units.

I started the thread because my comment was too long for the comment section.