so, besides the alpha/beta sessions that were meant to be anybody could just play? even without the meteors?

Skaianet distributed the game as a world-wide release on Beta Earth so as many people as possible could have a chance to escape the incoming meteor rain- But in the Alpha-verse and in the Troll Session, the code is taken by individuals and not spread around. Only the main Session is necessary, and only the Sessions that aren’t Void or at least have the Frog Temple will make meteors rain on the planet. Remember how the Alphas only had 9 Meteors? The 8 to bring the Kids and the Guardians, and 1 for the Frog Temple. Other than that, the major threat to the planet was Condy taking over and the Red Miles.