Maybe that is the best solution, Link. You know more about network programming than me. A disadvantage of communicating outside of JJ2 is that people have another connection and port to worry about. A major disadvantage of using JJ2 for communications is that JJ2 has sloppy netcode and data might be lost more quickly that way, especially in laggy servers. I don't think using JJ2 would make things very limited, I'm sure using memory manipulation pretty much everything can be done if you design some protocol. If you really want it simple you could even work using bits by just turning something somewhere off and on.

I'm not sure that there are already programs that can do a lot what I suggested. Using PC4 you can skip games, and change some server settings and the level, but it's not influenced by any actions so it's pretty much useless and can't do what's the point of a scripting language - replying to actions, which would make new gametypes and more interactive single player experience possible.

Let's do some more thinking.. how should the scripting language work? It will need to be able to test for certain conditions like player position or health, or joining/leaving players. There would need to be a continuous loop somewhere checking for conditions to occur. You can either have the people themselves create this (a script someone would make that would check for certain conditions would have some sort of loop, like most GUI programs have for example, something like main() I think, not sure), or do it for people, and have something in the order of functions in the script that are called each time a movement changes, or some way of setting up "listeners" (a bit like setting up mIRC script timers, syntaxwise). What would be the best? I have no experience with any, although I could probably devise some syntax that work could with whatever thing is best.