HaloMods "Classic" Read-only Archive

I've seen a lot of people do this. Even when others don't have their mod, they can still see the tanks, turrets, or ghosts. I have a mod where I switched the vehicles for tanks and turrets and I'd like to know how to do this trick so people joining the mod aren't turned off by what they see. *Note: I know that it takes more than just swapping the meta with the vehicles, it seems that the mods I have seen this done in have unlocked all vehicles on the map.*

Maybe it had to do with the whole editing some file to make custom gametypes? I wouldn't mind knowing the answer to this either.

No, because I played naked_chick's mod and it was just a map that I downloaded. I think he did something you couldn't do with HMT. Like hex or something.