Firstly, set tech research to horticulture and all cities except Babylon build wealth; Babylon will build a fairground first, then a textile factory, then a Royal mint
Send a phalaginte to India and conquer 2 cities you will find less guarded. They can easily kill spearmen but not javelins. Gift those 2 cities to the Sungas and you will get 6 elephants! Voila, the game is now easier
Exchange techs with the Indians now that you are friends with them, and send your units to Jerusalem.
The other starting units will attack the following cities with the following order : Tyros -> Antiocheia -> Tarsos -> Ancyra -> Ephesos -> Byzantium -> Pella -> Athens. Grab mercenaries you need only; I Hired a horse archer and a heavy spearman.
I conquered the Antigonids and Greece by 272 BC with my 2 starting elephants (combat 1 both), a mercenary horse archer (combat 1, shock and flanking 1 upgrades) and my other phalangite (city raider 1+2). I only lost a mercenary heavy spearman. By that time my 6 elephants arrived from India outside of Jerusalem and were ready to unleash doom at the poor Egyptians!
Send the slaves you captured from this expedition back to Mesopotamia and start building farms and cottages around Babylon and Seleucia.
Egypt fell at 255 BC and 1st UHV checked OK, meanwhile I had declared war on the Romans when they spawned, so they couldn’t surprise me later. I Had stationed my 2 starting elephants at Pella and I send there my 1st Great General to give them xp to face the Roman legions. I also hired a level 5 archer who would keep them away from attacking Pella or Athens. The legions appeared the turn I destroyed the Egyptians and promoted my elephants to shock & combat 2.
Using smart maneuvers, I destroyed Apuleia, Milan and Rome by 212 BC. I got lots of gold which is useful now that your economy is collapsing. Tech rate was at 0% by the time I had conquered Egypt. After the destruction of Rome I offered them Peace and get all their remaining gold. Poor Romans, it will take them centuries to recover!
Meanwhile I had declared war to the Nubians, using two elephants, and because they had longbowmen I was only pillaging improvements for gold. Then some barbarian attacked them and when their capital was weak, I destroyed it to get the gold. Then again I offered them peace for the remaining gold.
I fired every mercenary I had and focused on building up my economy, thankfully the Bactrians appeared and flipped a city! This means less expenses! Also since I got tons of slaves after destroying so many cities, some of them were used to improve the land in Greece and Egypt, and some joined cities (cities produce more wealth with slaves settled in).
These 2 Elephants who returned victorious from nubia, were sent to Tyros, alongside a starting phalagite to wait for the Maccabees to spawn.
By now, Babylon should be close to finishing the Royal mint, and have farms and cottages around her, this will boost your economy and you will be finally able to switch the tech rate to 10% ! Build a market also to improve her gold output even more, and then let her build wealth, with these you can now let 2 other cities that already build wealth, build fairgrounds and textile factories. And like this, step by step you must build these in other cities. When you reach a certain level of gold profit, your greatest cities must build your UB and start producing your UU. You are going to need them to face the Parthians.
My second Great General spawned while fighting the Maccabees and I used him to upgrade an elephant to have bonus vs missile cavalry (and of course combat + 100% exp gain).
Then the Parthians spawned and they flipped Persepolis and captured Epiphaneia. I used my gold reserves and hired all mercenaries available each turn. Soon I re-conquered Epiphaneia and took Arbela from them. My army was marching towards their capital; Persepolis will fall last.
After this successful campaign against the Parthians I still had some xp to gain to produce a 3rd Great General, so I declared war to the Pontus. Soon and after destroying the Pontus and some more barbarians I got my last Great General and won the game!
Enjoy your ‘Alexander the Great title’