Okay so I would like to make a game, I\'m trying not to divulge what it is but it requires anyone of a certain level in the game who is currently playing to be able to see e
If you need to create your own game since the beginning, you should use an IDE. But this is really LONG and sometime difficult. With a Game-Engime, a big part of the game is already programmed (physic, 3D animations...) so you can focus your time for program your game.
For play online, you should create your own server.
For create an MMO game, you must be logic.
First, you should create a client.
The client is the game
He contain the sounds, the graphics, the scripts...
Second, you should create a server.
The server is connected to all clients.
He contains the databases (Accounts, characters, HP, gold...)
So where started?
When a character move (from the client A), he send his new position to the server. The server send this position to all the client. So the client B know where is the character of the client A and can draw a tileset (in your example, you can draw the tileset only if the boolean sameLevel is true).
Take a look at the sockets:
http://www.linuxhowtos.org/C_C++/socket.htm
http://www.nullterminator.net/winsock.html
https://stackoverflow.com/questions/tagged/sockets%20c%2b%2b
https://stackoverflow.com/questions/tagged/sockets+c
Hint - I have already answer at some similar questions. Even if the programming language are sometime different, I give you the link, the logic is always the same so it can maybe help you:
Creating a Multiplayer game in python
Multiplayer game in Java. Connect client (player) to game that was created by other client
How would an MMO deal with calculating and sending packets for thousands of players every tick for a live action game?