I loved Karthadastim, though it is easymode. My greatest challenge was grinding through the Ptolemaioi horde. There were just. So. Many. They had already conquered the entire Seleukid empire, so my conquering Egypt simply meant closing one front and opening another, bigger one. While getting further away from my home base.
Ultimately I had one awesome general who conquered half their empire. He grew up in Lepki, which was under near-constant attack by them, and had to defend it with whatever troops I could spare from my Italy, Britain and Iberia campaigns. Once I had secured my other borders, I was able to throw an entire army behind him. He even became my faction leader.
The drive through the desert was glorious. Battle after battle left thousands dead, and my elite army drove all before them. I conquered all the Lower Nile, but did not have enough troops to drive back the growing horde while conquering the Upper Nile. I basically left a few dribs and drabs behind to contest Maroe, Axum and Therom, but even supported by local conscripts they were barely able to break even.
Meanwhile, my star general was sweeping through Palestine, while I launched amphibious assaults along the coast of Asia Minor using cheap Greek locals as expendable shock infantry. My plan worked. I captured Side, Tarsos and Halikarnassos, using Rhodos and Kypros as bases. By dividing the enemy, I was able to swiftly conquer everything from Sinai to Syria, losing nothing more than some Greek goons.
At this point, I was at a crossroads. The rich and valuable lands of Asia Minor lay open, cut off from the heart of the empire in Persia. Yet chasing one would leave the other to attack from behind, potentially destroying my precious army and leaving everything up to Alexandria vulnerable. I decided to send my champion after Asia Minor, and sent a raw, untested jerk with questionable attributes on a semi-suicidal mission to Babylon. His mission was to capture as many cities as possible, destroy as many troops, and stall the advancing armies long enough for Asia Minor to be conquered.
And that he did. The line of battle stretched along the continent, from Charax to Karkathiokerta, and though the losses were terrible and cities burned like torches, it was held. My champion general crushed all opposition he faced, even facing off the Hellenes and Makedons when they got in his way.
In the end, he conquered Ipsos, the last free city. He passed away that year, partying like mad in the realm he conquered. I might have a combined screenshot of his stats somewhere.