Pontus is actually a pretty easy game (on M/M anyway).

Took the rebel towns in North/ Mid Asia Minor, Took Rhodes - which meant I was at war with the Greek States -Pergamon, Helicarnassus. Took Byzantium from Macedon (good sieges there - one of which I just put everything in the central square to circumvent the desert infantry poor morale), Sailed over to Egypt to take out the Nile (two or 3 epic bridge defences there), worked way up to Jerusalem/ Sidon/ Salamis. Took Tarsus/ Antioch, then the 3 inland towns to destroy Egypt. Took Crete from rebels, landed in three armies in Greece to take out Sparta, Corinth, Athens, moved up to take Larissa, Tylis and Thessalonica. It is now 237bc and the Brutii have finally declared war. Two large armies in Greece - one bribed, the other massacred. One more on its way South. Pontus high-level troops rock! Much greater fun rushing chariots around Roman equites/ hastati than having to face spearmen/ phalanxes with them.

I think the key was the rapid economic growth allowing lots of mercenary units to be hired, which thrashed the weaker forces.