I'm playing the good old D1 on my W10 PC. As far as I remember, I never needed to do anything special to play D1 (Hellfire is a different thing). If you can't play D1 - try this: https://www.reddit.com/r/Diablo/comments/4kdh3u/diablo_1_deserves_some_love_introducing/ . Works for me. One note: It really has to be 1.09, not the 1.09b. I dont play on bnet (probably no one plays D1 on bnet today) so I cant tell you if it works in multiplayer too. Also, no fullscreen mode - you can only resize the window but only after launching the game with any character. Not mine, I'm only reposting it here in case you didnt heard about it.