In my view, to really start a game with Unity.Let's use
Atavism, and start developing games from it. It's got everything covered, and is backed by a huge team.
Their sample game on the Unity side is made very similar to World of Warcraft.
The server part, written in Java language, has developed and fixed most of the features, has all the features that other MMORPGs have.
If you know how to customize the server source code, require knowing the Java language, and programming according to their documentation, then you will have your own direction and relatively save a lot of effort.
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Wait for the Black Friday sale, buy it. I think it's pretty cheap for most people who are interested and passionate about game programming.
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Also to really clone a certain game, and start developing to make money. It is best to understand the source code, and how the Chinese source codes work.