I was reading the configuration for steam authentication and noticed that a single app id is needed. What if I want multiple games under the same publisher to be accessible by the same nakama user and authenticated via steam, is that possible? Or do I have to make one server per game, which in turn requires a new nakama user per server.
Nakama is designed as a single tenant system and cannot (easily) host multiple games on the same instance.
In case of Steam, it is not possible to have multiple Steam Apps integrate with a single Nakama instance.
Beside this limitation, there is no way in Nakama to bind a single Nakama User ID to multiple Steam IDs. I suggest you separate your User ID source of truth from Nakama and Steam and provide a mapping yourself - this could be possible made into a BeforeAuthentication Hook.