How can I make A place only accsesible through playing A game

I have A game where the lobby is the starting place (In the place folder has an image of A spawn location) and my actual game has A planet
How can I make it so that the player cannot join that game unless they go into the lobby or is it already like that?

I believe it is already like that.

To confirm, yes it is. And if a player tries to join the second game it will just send them to the start place instead.