It should be possibel to set up multiple variations of 1 game in multiplayer. Let's say the game is called 'hello world'. Multiple 'rooms' of this game can be hosted and then be joined by peers I asume? The host makes a new game/room by giving it a name and peers can join randomly or by giving in the exact game or code to enter. Am I correct that this is possible?
This is correct.
If this is the case my question is this: How can I receive the info of a single game/room and see how many peers have joined a room/game? Is this possible and how is this done? How to check how many games/rooms are active etc?
Any ideas? I hope you can help me out a bit.
You can get information regarding rooms via the multiplayer actions and expressions described on the multiplayer manual page.
Here are the ones in particular you would be interested in -
Request game instance list
Request a list of active game instances within the given game. When the response is received On game instance list triggers and the name and total number of peers in the returned instances can be listed using the List... expressions.
Request room list
Request a list of active rooms within a given game instance. The returned list can include all rooms, only rooms which are unlocked, or only rooms which are available to join (unlocked and not full). When the requested list is received, On room list triggers.
After On game instance list triggers, the number of game instances in the received list.
Get the name and peer count of a given game instance in the returned instance list.
After On room list, the number of rooms in the received list.
After On room list, retrieve information for a room at an index in the received list. The state can be one of "available", "locked" or "full".