I wanted to know if there was a way to make a Mod, make it multiplayer, and allow ingame joining. Is that possible? By any means, sort of way? If not, can you do it if it's not a Mod?
You mean like Diablo II where you can join a game in progress? No you can't, StonedStoopid was working on it, but I don't know what happened to it. It was for FPS Mod.