Heroes of the Storm, the game previously known as Blizzard All-Stars, Blizzard Dota, and Blizzard Entertainment Presents A Bunch Of Guys Hitting Each Other, is technically in alpha. Wait, sorry, that's not right. It's in technical alpha. That means that it's in a phase of testing with an emphasis not on balance or gameplay but on making sure that the fundamental engine works. Testing is currently limited to a very small pool of players, but external players are being brought in to really put the game's network through its paces.
Players who cannot wait to get in on the game, even with placeholder graphics and numerous bugs, should make sure that their Battle.net accounts are up to date and have opted in for the beta. Again, invitations will be extremely limited at first, although the roster of testers will expand as time goes by. If this sounds like your sort of gig, make sure you've opted in, and stay hopeful that Blizzard will grant you a coveted invitation mail.