MOAR BYZANTIUM YOU SAY?!
My current Rome game in the Death&Taxes mod, awesome, so far i've beaten massive Mamluks, Austrians, Hungarians, Frenchies, Brits and Mughals
World :
I'm allied with the mighty Novgorodians, they are waiting for Moscow to core so that they can form Russia

(they annexed vassal Muscowy some years ago, so soon it will core)
HRE Burgundy, massive Bavaria, and lots of other blobs in the HRE are orthodox, i force-converted them some time ago, after orthodox pwned-Austria lost the crown, thanks to few ellectors being orthodox.
Just mah empire :
I had allied with Bohemia and just diplo-vassalized them, now i will become emperor! i need to leave the HRE btw...
BONUS!
There's a map of the world when the Austrians (same dinasty as me and still allied at that time), Mamluks, Mughals and even the Hungarians were still strong, the Mamluks and Mughals were at their power peak, they were massive, had massive armies, and no one near could beat them, until i started expanding there

England was not at their peak, they would colonize most of South America and annex most of Morocco among other territories before it, they would be massive, until i started the Reconquest of Ragusa and ROFL Pwned them at North Africa with a awesome general and 16.000 soldiers, this destroyed their WE and made them release Tunisia (Diplo-Vassalized to me later) and some other catholic africans (Algiers and even Tripoli) revolted, Tripoli however, was annexed in a war their allies started...