balynn: It's abandonware.
*removed abandonware link*
it's been on this site for ages. Regardless of legality Blizz didn't care apparently. That may change now with the GOG release.
CymTyr: The Diablo series has never been abandoned and by logic could never be abandonware. Your link is also against TOS.
Definitions of "abandoned" vary, but in general it is like any item that is abandoned – it is ignored by the owner, and as such product support and possibly copyright enforcement are also "abandoned". It can refer to a product that is no longer available for legal purchase, over the age where the product creator feels an obligation to continue to support it, or where operating systems or hardware platforms have evolved to such a degree that the creator feels continued support cannot be financially justified. In such cases, copyright and support issues are often ignored. Software might also be considered abandoned when it can be used only with obsolete technologies, such as pre-Macintosh Apple computers. A difference between abandonware and a discontinued product is that the manufacturer has not officially 'discontinued' the software, but only ended their official efforts at technical support.
Yes Diablo 1 WAS definitely abandonware prior to GOG's release.
No the IP was not abandoned, however Diablo 1 was no longer legalally available for purchase nor supported by Blizzard. Thats abandonware by definition.
"Abandonware is a product, typically software, ignored by its owner and manufacturer, and for which no support is available[1]. Although such software is usually still under copyright, the owner may not be tracking copyright violations."