[mdpane]

To write a secure online multiplayer game in javascript, the server would have to assume the client has been compromised by default and verify everything server-side. This wouldn't work for anything fast paced, but it'd suffice for RPGs and puzzle games.

For example, in an RPG, a client says it's moved 5 tiles north. The server receives it, but before broadcasting it to other players, the server would have to read the map and make sure it's valid (e.g. there's nothing in the way).