OGame Alliance Chat is a script that allows alliances to chat in real-time and in-game through an unobtrusive box in the lower right corner.
The script connects to a server running node.js and thus running the chat server. I'm currently hosting that but the server is open-source so any alliance can host their own server for privacy or stability reasons.

Since I do not have access to OGame session data, the script has to trust user input.
To prevent spying on alliance channels I had to impose passwords that are set in the database.
You'll have to request an alliance password from me or whoever is hosting the server, since allowing users to change passwords at will would obviously cause issues.

It's a rather simple process in the end.
Install the script, request an alliance password and once you receive it, enter the password in the OGame chat client to chat away!