I'm curious why did you feel the need to make diablo 2, I mean why not something similar but original?
I think its a shame to put so much time and effort into something that's just a blatant copy.
If this gains a lot of popularity blizzard will be very likely to shut it down, so is it really worth it?
Because he wants to? For practice? For fun?
Obviously he has some fond memories of Diablo.
Looks awesome so far keep it up!
I still will recommend not copying or trying to ride off the fame of another title.
OP should keep everything hes done and continue to work on it but steer away from Diablo to the point that it's not a Copyright issue.
Trust me blizzard will not allow Divinity Original: Sin to make more sales due to a Popular Addon: Diablo 2.
Also just because something is free or mod doesn't mean its not illegal or theft under copyright law which this is... (I like it how the community supports such things when it suits you)