I just came up with a killer strategy in this game.
Using mid difficulty.
*At start, create 4 legions.
*Take over Sicilia, Africa, Sardinia, & Gallia Cisalpina with max 4 losses (else restart).
*Defense 2 legions in Gallia Cisalpina & Africa.
*If you have any Legions left, keep pillage provinces, but don't keep any defense.
*Civilize any provinces inside your defense.
*Don't worry about loosing provinces outside defense border.
*Slowly expand the provinces that has defense, but use as few provinces defended as possible, is possible avoid provinces that border to yellow spawn provinces.
*Pillage alot. Always build full amount of Legions and keep pillaging to all but the defence are dead. They have too expense upkeep.
*Only build Limitanei in provinces bordering to spawn points.
Progress report:
*275 ACE, score 1099 - 233p/turn, 34 provinces (all). 12 Legoins, 3 Auxilia, 5 Limitanei. Defence in: Africa, Mauretania, Brittania, Germania Minor, Raetia, Illyrium (3-4 units in each, keeping defense in west side, leaving mid+east side open for pillaging next turn to get more cash). Most barbarians now have 8 strength, getting harder and harder.
*525 ACE, score 2005 - 158p/t, 18 provinces, 16 Legions, 3 Limitanei. Defence in Africa, Mauretania, Brittania, Germania Minor, Raetia, Illyrium. Most barbarians now have strength 10. Destroyed 312 barbarians, lost 182 armies. Could take back all lost provinces each turn (game stopped before I got the chance on last turn).
Game end: Civilized 13 provinces. Recruited 185 Legions, 4 Auxilia, 10 Limitanei.
Game crashed when submitting score!

On the next to last turn, I could not civilize provinces (had enough money, and I startex civilizing them, but when I exited the province it was not civilized, have seen his bug before).
Edit: Have a save from turn 475 ACE.