Even though Diablo 2 has been available as a "classic game" on Battle.Net for years, Diablo 1 never has been...until now. The game has never appeared anywhere else except in physical editions. However, all that has changed with today's release of Diablo 1 over at GoG.com for $9.99. This marks a turning point for Blizzard games that have never appeared in any other form than physical and / or on Battle.Net.
The announcement was made on the Diablo 3 site where it reads in part:
Q: What is different between the Battle.net and GOG-enhanced versions of the game?
A: The original Battle.net version of the game is completely unchanged and allows players to connect to one another through Blizzard’s Battle.net online-gaming service.
The GOG-enhanced version offers several quality of life additions, including minor audio fixes, up-scaling support for resolution and refresh rate control, and compatibility fixes. Please note that this version cannot connect to Battle.net and only supports multiplayer via LAN and P2P connection.