The first recorded convert to Judaism was Ruth, heroine of the Book of Ruth.
Taoism is hugely significant (and is the same thing as Daoism). And Judaism is more recognizable, more influential, and apparently more resilient than Zoroastrianism. It's also closer to purely monotheistic, Zoroastrianism is actually dualistic.
If in that since Zoroastrianism is dualistic, Christianity is tristic (ok, thats not a word, but you know what I mean)
Ok, so maybe Zoroastrianism being unlocked by the same tech that unlocks Judaism is bad. Maybe that wasn't the best example. But I think you get my point.
the seven religions is the game are:
Judaism
Hinduism
Buddhism
Islam
Christianity
Confustinism (ok that was spelled wrong)
Doaism.
In modern times, in terms of raw numbers of believers, yes Doaism has quite a bit more! But civilization is not a game limited to modern times. The modern age is just 1/6 of the game!
Here in the west, Judaism is more influential and recongnizable. If you went to India, that might not be the case. Just like civilization is not limited to the modern age, its not limited to the west either.
You make it sound like I'm trying to kick Judaism out of the game and replace it with Zoastranism. This is far from the case. I recomend not kicking out ANY of the religions that are presently in the game. All I'm suggesting, is add some other religions in as well! (and of coarse, let the players "choose" during the game, so as not to upset the perfect gameplay balance of 7 religions.)
Let us not forget that Zoastanism had an influence on the Abrahamic religions (Judaism Christianity and Islam) after Zoastranism influenced Judaism, Judaism influenced Christianity and Islam. So in a since, Zostranism influenced Christianity and Islam through Judaism. If you read some of the belives and striptures of Zoastranism, you'll find some of it shockingly simular to Chrisitanity.
This would also be great for RFC. This way, Rome Greece, Persia, Aztec, etc won't have "no religion" until they convert to one of the modern world religions. I guess they could mod in "roman polytheism" for rome, "greek polytheism" for greece, "zoastranism" for Persia, you get the picture...
The Persian empire was once the biggest empire in the world. You can't say they had little to no impact on anything.