Yeah, I agree this is a good discussion. Ignore that other guy.

I am currently working on a mod inspired by the original Diablo. But to avoid copyright stuff, I am avoiding using the same NPC names, the plot and story will be rewritten to be something new (I have a neat idea for an ending already), I have a musician who is helping make some music. However, the main town (which I renamed also) has the same basic layout as Tristram. The Cathedral is planned to have 24 levels (big project, I know)

I've been doing my copyright research and found that you can not copyright ideas, names, facts, or concepts. It's like walking on eggshells with this stuff, but given the right amount of changes people should be ok.