Is your feature request related to a problem? Please describe.
Right now there is only one room/gamemode: FFA. There is no real way to only play with friends, you will always end up in the same room and there will always be other players.

Describe the solution you'd like
I would like to let users be able to join rooms by using a GET parameter (?gameid). If a room with that ID does not exist, it will be created.
In the main menu we could add a button that allows users to create rooms or join a specific one or a random one. If no gameid GET parameter was provided, they will end in a "main" room.

Describe alternatives you've considered

• Limit rooms so there can't be tons of rooms which could potentially kill the server.

Additional context
Other .io games have a similar feature which you may recognize as a "party". It's a special room where you can play with other people you know.