"The Etruscans Strike Back", Firenze->Tuscany->Italy->Rome. Nothing too great, but it did get me 8 achievements:
Grand Duchy, Italian Ambition, A Protected Market, This Revolution was Crushed, All Your Trade Are Belong to Us, A Decent Reserve, Just A Little Patience, Mare Nostrum
There was a lot of suboptimal play involved. I was hoping to get an electorate to stay inside the HRE, was already too big (but too small to expand outside Italy at the time) when the Catholic Empire happened, managed to PU an electorate OPM, basically lost too much time. It wasn't like I got anywhere near forming the HRE, teaches me to never settle for greyskin. I also wasted 10 years trying to Crush This Revolution happening in the half of France I had yet to annex at 1800 so that I never had to worry about that achievement again, and only ever got to take Crimea after that.
Managed to turn into a kingdom by forming Tuscany with a Medici on the throne. I then lost them around the 1700s in a series of complicated events where the Maghrebi&Iberian lands of Portugal were one province larger than 100% OE, so I took all of that and almost all of European Spain which roughly gave me 280% OE. See, I was about to have a civil war and assumed that would stop separatists from spawning, letting me go through the 2 year coring phase with relative ease. My heir got the throne that month. So, Greece managed to spawn because I missed Rhodes' occupation until 4 months before they won and my entire navy was in Londinium (kind of weird how they get wholesale independence when they only held to an island), I exported swathes of South Slavic rebels into Ottomania, and I ended up capitulating to a revolution. I tried to go for the Bureaucratic Despotism route; the 10 times reelected genius died 2 months before that happened and left me with a 1-4-1. His heir was a 3-2-0. Around the 1790s however, through a marriage to Poland whom I had infected back when we were friends, a De Medici finally reassumed the throne and recreated Rome. They also rule Russia. I do wonder what that apostrophe in De ' Medici is from though. Is that a bug or Medieval Italian?
All the histories aside, I imagine if this was attempted by a player more skilled than I (not a hard thing to be), they could have easily achieved the borders I dreamt of.
I also had fun using a dictionary and the Latin Vicipaedia trying to figure out names for all my armies.