The MOBA space is getting crowded, especially with Blizzard making its entry with its take on the sequel to Defense of the Ancients (more popularly known as DotA).
About a year ago, Blizzard and Valve came to legal blows over the DotA name after Valve revealed that it would be titling its sequel to DotA the very aptly named DotA II. In the end, Valve came away with the DotA trademark and Blizzard was forced to name its DotA sequel Blizzard All-Stars.
Blizzard's announced that All-Stars is being renamed Heroes of the Storm, probably because it figured out that the All-Stars name might be a little bit confusing, in light of Sony's PlayStation All-Stars game.
The developer's also announced that more information is to come about the MOBA during BlizzCon in November.
As for game abbreviations, sources inside Blizzard refer to Heroes of the Storm simply has "Heroes," leaving the HotS for StarCraft.