Background
The MMORPG in question has a Korean developer and a German publisher. It is pretty old, but is still live and running by the publisher. The game appears to be dying and has a very low active population in general. The EULA seems to prohibit packet-sniffing and reverse-engineering to "reproduce ... the games" by the wording used, however that does not seem to make it illegal. Merely voids ones contract between emulator-developer and the publisher, giving them the right to ban use of their servers/services, if I am not mistaken.
There was an excellent answer, in my opinion, on a related question in Law StackExchange [1].
I am a European citizen. It is meant to be a hobby project originally, but seeing as how much time it takes to execute, it is sad to not see the effort be financially profitable, especially considering the potential it may have. The intention is first to replicate, and finally to modify by changing experience point rates, quests, maps and more, to re-form the entire flow and experience of the player, differing from the original game.
There are leaked server files and possibly leaked source code to the server files, but I will not peek at neither the reverse-engineered leaked software, nor the leaked source code, as it defeats entirely the original purpose. Hence, unless I misunderstand, the "Chinese Wall" principle [1] applies, since packet-sniffing and reverse-engineering of the game client are the tools used.
Unless I have misinterpreted [1], the game client appears to be the major stopper, before even getting to the financial aspects.
Questions
If at all possible, how can one go from writing the MMORPG server emulator, from scratch, to running a profitable server, legally, for the specific game described above?
Also, an auxiliary question: is breach of the EULA illegal or immoral, in this case?
Edit
I want to explicitly point out that, as per [1], the server emulator would not be theft of code, but a recreation from the imagination. The work-flow to produce the emulator only involves dissecting of the game client and packet-sniffing of the communication between the original game server and the game client. The EULA does not state any legal action against these two methods. I have also added a secondary question to help out the discussion.