Serverlists are the main feature of the Unreal Software Gaming Network.
New game servers register themselves at the U.S.G.N. masterserver when they are created.
The masterserver saves the IP and port of the game server and adds this data to a serverlist.
Players can request this list and can get an overview over all currently active game servers that way.
When a server is shut down, it informs the masterserver so that it is removed from the list.
It can happen however that servers crash or are not shut down properly.
Such servers would normally stay in the list forever because they do not de-register at the masterserver.
The U.S.G.N. is using a heartbeat approach to solve this issue:
Every server has to regularly send a message to the U.S.G.N. in order to signal that it is still online.
If a server does not send hearbeat messages for several minutes it will get removed from the list automatically.
Users can log in in-game with their UnrealSoftware.de accounts.
This login also works over the U.S.G.N. masterserver.
The corresponding account ID can be used to distinctly identify users.
This is important for things like permanent bans or admin rights.
The website allows users to add other users as friends.
In-game there is a friends list which allows to see the online status of all friends.
Moreover you can use the list to easily join friends on the servers they are currently playing on.