I lov this game. However, I really want to play a “conquer the world” scenario, and the game tends to be pretty limiting about that. It won’t, for example, let me get beyond the “conquer Rome and 50 provinces” end of the scenario.
That makes me a sad Panda.
Is ther any way to extend it so I can continue forever?
R:TW is one of the most thoroughly modded games I’ve ever seen. I’m certain that there’s a simple mod to allow this.
I think you can just go into the text file and alter the bit about where it ends.
So yeah, I think you can do exactly what you want to do.
Oddly enough, I couldn’t find one. I think the key here is “thoroughly” modded. People go out and do huge, total conversion mods. I haven’t seen any mini-mods. 
Okay, my install of R:TW has got the Total Realism conversion mod applied and I can’t find the relevant file in that. But I suspect that’s cuz the RTR mod has moved it. The following is true of what I can find in R:TW mod forums, and in my M2:TW vanilla install.
Look in Rome Total War\data\world\maps\campaign\imperial_campaign, and there should be a file named descr_win_conditions.txt. Open it in notepad, and you’ll see something like this:
venice
hold_regions Constantinople_Province
take_regions 45
short_campaign hold_regions ;Constantinople_Province
take_regions 15
outlive milan byzantium
This example is taken from my M2:TW install, obviously, but it should look really similar in R:TW. Adjust the parameters as you desire. You have to do it separately for each faction, though - but run a find & replace changing 45 to the total number of regions should do it all in one go.
Hope that works. I suppose I could do a vanilla install of R:TW to verify this, but I think I’ll let you do that part of things.
You don’t need to mod it at all. After you win, you just keep playing. I think you might have to select “Continue” or something like that but it’s not like the game shuts down. I’ve conquered the world many times like that. What’s the problem?
That’s odd. It didn’t give me the option. 