i had this idea yesterday
i think we should have an "invite a player" button like in bots. the prize for who invited someone should be something "desired" amongst players, something that makes them invite as much friends as they can. to make invited players stay they could get something like a short membership or a "starter kit" that helps them for the first times (something that's only useful for low levels and that wont make anything op" and maybe someone will actually stick to the game.