Then, a mod group called Rivsoft made the game playable for anyone with a web browser over at diablo.rivsoft.net. You can download the Devilution group’s source code, and just drag and drop it onto the screen to start playing.

If you own an actual copy of Diablo, you can drag and drop the DIABDAT.MPQ file from the game’s installed folder to play the full version. You can get more details here.