The modern day country of North Macedonia corresponds to the territory of ancient Paeonia which was landlocked and never settled by Greeks. The region of Macedonia which you are probably wondering about and corresponds to the ancient kingdom is located almost entirely within modern day Greece and is included as such.
Based on P. Christiaan Klieger's "The Microstates of Europe: Designer Nations in a Post-modern World", Monaco was settled in the 6th century BC by Greeks from Marseilles (Massalia on your map). At the time it was known as Monikos. Monaco should probably be included then.
Possibly not the Vatican, as I don't think Rome was ever under Greek control. Unless of course those who think the Romans descended from the Trojans are correct, but that seems unlikely. They traded with and were heavily influenced by the Greeks, but were not Greek themselves.
I don't see a key but I'm assuming that the dark blue areas on the map are "Greek," and if that's the case then the land currently part of the country of Macedonia would be in the hands of Thracians and Illyrians, not Greeks.
Thought it was odd that Croatia was on the list, but not Slovenia, not Bosnia, not Serbia - but Albania. I decided not to look at the map until after, and now it makes more sense.
Now I wonder this. Norway is least guessed on countries that have been part of Norway. Egypt is least guessed on the countries within three countries of Egypt quiz. What makes Greece higher guessed than those cases here? At least I got it. (I made sure to do it first to make sure I don’t get confused and try like, the whole world).
This one went against any of my logical reasoning lol, but I've managed to name them all. For example no North Macedonia but Russia and Spain were in. No Israel, Lebanon or Jordan but Turkey, Cyprus and Egypt were in. Once I looked at the map it made sense.
Could there not be made an argument to include Bosnia? I looked long and hard on the map on which this is based and thought it might include the most southern part of Bosnia.
I think @ShievaAndGolly is saying that the "the" in between "on" and "this" in the caveat is probably a typo, and I agree. I didn't notice it until they pointed it out. Funny how the mind just glazes over minor errors like that sometimes.
https://www.theguardian.com/science/2018/oct/23/oldest-intact-shipwreck-thought-to-be-ancient-greek-discovered-at-bottom-of-black-sea
According to the source (the map that is linked), the entirety of the modern day country is located on Greek settlement lands.