this is a really good idea for other people to do not me 
, and the best programm to use would be gm.
Gm would lag terribly. A full fledged programming language, like C# or C++, with a good graphics API, like Direct X or openGL, would be much more appropriate for a project like this.
As far as 20-40 people...large numbers dont' necessarily yield large results. Especially online, do you kow how hard it is to coordinate a team of that size?
It's an interesting idea, but with that much creative power behind it, why not do something new and exciting, instead of just a retread of an old game? I don't think a lot would be added to lttp by making it 3D. In some ways, I think it would probably lose some of it's feel.
