Come on, IJ is fun and easy to play even on VH/M. First crush the northen barbarians, create the rhine frontier again, defeat the Visighots by sending Julianus himself to deal with them, and keep Edessa in your hands. Brittania is easy to control, dont advance north, if the picts invade, send your legion to crush them. The Franks and Alemanni can too be defeated, there are enogh troops in Gallia to create two armies, move the Palatina legions to threaten the soft underbelly of the Alemanni. The Iaszyges where more of a problem due to their horse archers, but there are Sarmatians and Alani ready to serve the Emperor. It too me time to kick them out and restore the limes on the Danube, they even captured Callinicum, and the city was freed after alomst 10 years. The Sassanids of course forced the Persarmenains and Lackhminds in an alliance and they betrayed me. Of course the main threat are the Sassanids, there are the Armatus Palatine in Anthiocia, recruite a legion of these veterans and crush them.
You should heavily invest in the East, it is the richest, then begin a building progaram in the West, money will flow, giveing you the opportunity to build barracks are create new legions. Dont conquer or desroy the others, the game will be no fun, just take what you need. I conquered Petra and Argentoratum, renaming the later Arg. Juliana Flavia. if I have the time, I will post some pictures of the rebirth of the Roman Empire. ( How much i loved that this would have happened in real History.

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Cheers.
Cheers.