I am creating a MOBA game and I will host tournaments which will be visible on the website. to join the game, you must be logged in on the website and browse the tournaments list and select a tournament and click play.
Clicking play will launch a custom protocol like
and the game client will open for the given tournament id.
Now, I don't want the players to login again on the game client, I want them to automatically login because they are already logged in.
How can I securely log them in automatically with this idea?