For those that don't remember, this was actually a pretty neat system and prevented the LAN playerbase from being split or limited by their ability to connect to the internet. If you were a Halo 2 or 3 1.0 joining a later version, you would inherit the changes as everything they changed was determined by the host anyway. So you could be 1.0, join a 1.5, and your BR would get the super tight spread and the better grenades, etc. In Halo 3, you'd have the simulkills happen. And it worked the other way too. If a future Halo 3 or Halo 2 joined an older version, they'd silently regress to that version. So if you're on 1.5 and join a 1.0, your BR would get the bigger spread back, and you'd get the flying melee deaths in Halo 3.