Fluffy, sometimes you suck..
There are more than one way to make IVAN multiplayer, he just needs to find a way that works well enough. And if Serefan loves programming so much that he's willing to port IVAN to Java(madness!) then he's probably got enough willpower to try a few different solutions.
But I see where you're coming from, fans of games tend to have utterly game warping ideas like this all the time(multiplayer oblivion, counterstrike in UT, mana/magic system in IVAN). And obviously it's a bad idea most of the time and they wont actually have the skills or energy needed to go through with it properly.
No reason to mock them like you do.
All the power to you Serefan, Java is my prefered language too btw
As for tunnel generation, I suggest you search the web for maze generation algorithms, the technique should be the same. And do look at the source code for IVAN. Java and c++ isnt that far apart.