Can someone tell me how to install the belzebub mod? I have the original diablo 1 but I do not know how to install the mod, I appreciate the help of everyone who can help.
You need just copy DIABDAT.MPQ to it.
Download Belzebub _https://mod.diablo.noktis.pl/download
Then, unpack archive with files to any folder ("Belzebub", for example) and copy DIABDAT.MPQ to it (from installed GOG Diablo1).
Also, you can just extract all files from Belzebub to installed Diablo. That's it.