: Tools like DxWrapper allow for a "No-CD" experience by patching the game to look for DIABDAT.MPQ locally on your hard drive rather than searching for a virtual or physical drive.
There are "Diablo in the browser" projects (based on DevilutionX) where you can simply your legal DIABDAT.MPQ file into the browser window to play instantly without an installation. Quick Technical Notes diablo 1 diabdatmpq 2021
In 2021, the most "interesting feature" associated with the file for : Tools like DxWrapper allow for a "No-CD"