ROMA VICTRIX!
Needless to say you can play as I did as the Western Romans and from 363 A.D to the end of the game 476 A.D you are just battling to keep the empire from crashing down like it actually did. I was totally convinced playing as the WRE was supreme folly. I read advice from this site and others for strategy & tips and they worked, cuz the KEY to winning is stabilizing your economy in the first few rounds and slowly getting your field armies (Comitatenses troops) trained and assembled and where they are needed ASAP. The Huns are the biggest threat I thought and when they arrived in my empire there were like 8 or 9 "stacks" of them and the ONLY two strategies that will save you in battle with the hordes is either 1. forming a full army of yours into a cavalry square with archers in the center or 2. picking and defending a bridge and let the bastards come to you! I guarantee these both to work, I had nothing but victory after victory after suffering one major loss to the Franks (which horded after I took their only city-bad move). I used the square against everyone except the Huns, they have way too many horse archers and they would just wear down my infantry with their arrows. I defeated them in earnest guarding a bridge by a city named Equincum and they were finally neutralized, if not killed.
My other major tip to offer is DO NOT MESS WITH CONVERTING YOUR EMPIRE TO ONE RELIGION!!! Period. I did that around the year 428 A.D with about 8 of my provinces in Gaul and the next turn ALL of those MF's threw off the Roman yoke! Then it was like dominoes falling! The economic & political crash that usually happens in the beginning, happened way later instead but by my own doing. All those weak governors and disloyal generals switched on me and joined the Western Roman Rebel faction, I was beyond angry, I was catatonic! lol Here I had beaten the short objectives, won the game but kept playing and I was doing just great. Granted my Empire was fine for the WRE of 476 but paled to what they really did in 100 A.D at their peak. Even though I had beaten them like 99% of the times, The Eastern Empire is a hard nut to crack and their navy is too strong. I was stalled as far east as Alexandria with none of Asia Minor, Persia, middle east or any of the Sarmatian lands to the northeast taken at all. Of course, all the cities just don't produce $$ like they used to and the raising of huge armies costs alot and takes time. Plus you have the northern borders to constantly defend from the Burgundii, Lombardi and Saxons (My erstwhile allies, The Burgundii gets props from me I never got attacked by them and they acted as a fine buffer state between Rome and the Lombardi). I was happy that after a few turns more I had either re-conquered some of those rebellious cities with some nearby armies. A pleasant surprise was when three of those 8 came back and did a "loyalist revolt" which was sweet they came back to the empire.
At this writing the Empire is steady but not really expanding to my liking not like in RTW where you just go all the way to Parthia and northwards too. This game is all about, keeping those armies intact, getting your cash cow cities to produce more and getting those hordes to face you at the nearest bridge!
Have fun with this one! I know I did, a few heart attacks are standard though it seems!
"Rome's Finest!"