How to simulate a game server?

Question

Programming

Continuation of the topic Where are the files to deploy the game server?
Interested in how

reverse-emulation off-server

What languages ​​are used? Is it possible to use software other than off-server software for emulation?
And in general, what difficulties will you have to face and where to dig to dig up treasures?
Lots of questions, few ideas.

Answer 1

Look at existing open source projects:
Read the source code, chat with the community on the forums - you will understand what difficulties you have to face, and what it costs.

Answer 2

Yes, how do you imagine it? Well, this is commensurate with the task of "writing your own game." Well, that is, imagine, the server calculates the physics or damage of one player to another, how will you emulate it or forward it to a real server?
Colleague, you are looking for a normal game, which has a normal public / server available for installation and use it.

Answer 3

What game is that?
As mentioned above, servers can do a lot of things. Including consider physics (WoT for example). In this case, it will be difficult to do.
In general, the approach should be something like the following. First you need to look at what the client sends to the server and receives from the server. By further analyzing this data and the behavior of the client, you can understand what the server is doing. Further, based on this, you feed the logic of your server, which performs the same operations.
In the general case, it is unrealistic to do this (UPD: unrealistic, I mean not technically unrealistic, but unrealistic in terms of cost-profit). Only if the server is really very simple.
UPD: You understand that you can't just save all the questions and answers from the off server and then just look for the most appropriate answer to the request?