1500 BC is a little early for a Grand Campaign...it's about a thousand years before the beginning of classical Greek culture as we know it.
Yeah but classical Greece is pretty dull compared to that era. And you have a huge Persian Empire which doesn't really help the concept of a Greek based game!
Back to the timeline I suggested you have various Mesopotamian cultures that can expand or Asia Minor tribes neighoring the Greek colonies like the Hittites, you have Mitanni, Egypt, and Phoenicians.
It's the closest thing to a mix of EU and CK imo. You have family dynasties in Greece controlling several kingdoms (eg Trojan war you have Agamemnon at Mycenae and his brother Menelaos at Sparta) and you have relatively empty map with various city-states that have lots of room for expansion (since much of the land will of Greece would be colonizable), some Greeks and Phoenicians who would be ready after some centuries to colonize the rest of the Mediterranean(where Spanish and French coasts as well as western North Africa would act like the Americas, Africa and Australia on EU series) and the Asians would look to break the Greek city-states creating either a panhellenic front or various alliances with inter-Greek wars inflicted by the rich eastern kingdoms!
So the three main points of focus would be diplomacy, military* and colonization in the way I have thought of this.
And as a state you can opt to have a patron god/goddess but not easy or impossible to switch to someone else (like Athens, Knossos and Troy with Athena) or you could opt for a pantheon like Megara (who didn't really have a preference)
And within Greece you can have better relations between the tribes (eg Doric => Sparta, Macedon etc)
The point would be to have a relatively small map, like the one CK has but centered on the eastern Mediterranean, so that you would have more provinces to colonize and spread your state's ideals, or if you wish expand as a Mesopotamian tribe(eg Babylon who would already be quite big) or Egypt and conquer Greece and the whole "known world".
And it would be interesting to see how the 'Dark Ages' would be tackled. My take is that some major disasters would randomly occur for 300 years (volcanoes, earthquakes, cataclysms) so you will lose a lot of infrastructure, population and manpower but you would be compensated with enhanced technology and population growth after the 8th century BC. There wasn't an actual invasion by the Doric people onto Greece, just a cultural change that came to effect due to natural disasters most probably.
* Military units could be made of lots of different infantry units (spear units, sword units, archers, peltasts, better armor etc), various cavalry units and also warships. Warships in ancient times were very interesting and there was also some famous naval races between city-states, essentially a King's hobby to have the best ship in the region, which was stopped because they run out of trees after some time
Starting at 500BC is just diplomacy at first and one will most likely fail as a Greek state so it's hard to use the military.
Starting at 800BC, Assyria was too strong and you have Phoenicians already all over the mediterranean and only a handful of Greek colonies.
1100-800BC we have the so called Greek Dark Ages, but we know that the Greeks were trading with others around 900BC.
Starting after Alexander's death you have a nice scenario for big states but the minor states are just there to be consumed, same thing people complained about EU:Rome.
Starting at EU:Rome's date, you can only achieve something as Rome, Carthage, Egypt or Seleucia and maybe Macedon if you're lucky.
So if you want a Greek themed game, you have to go back. And since Paradox has had great success with EU3, CK2 and EU4, this is the perfect period to implement aspects of both games. Anywhere from 1500 to 1300 that is as a starting point. This also enables the Trojan war (somewhere around 1200BC). Which means as the Mycenae lead alliance your aim is to conquer/vassalize mainland Greece and build a huge navy to cross the Aegean and as Troy to gain as many allies on the east or even west and try to stop the Danaans from attacking before they set sail!
