This game can be downloaded from the official website:
North America: https://us.battle.net/account/download/?show=sc2
So why do you need StarCraft II? Well, 11 million StarCraft fans can't be wrong. The original StarCraft made its debut in 1998, and it quickly became one of the most popular real-time strategy games of all time. We've waited a long time for an updated sequel, and rumors of it were periodically dangled in front of us like a space carrot over the years. So why did it take so long? Because that is precisely how long it took to fill it with the perfect amount of awesome. It's a continuation of the epic struggle between the human Terrans, the insect-like Zerg and the psionic Protoss. Fans of the original will see some familiar faces, as well as a cast of new heroes as they do battle across the galaxy with veteran, upgraded and brand new unit types. To remain consistent with the game's new-millennium feel, the Battle.net gaming service has been completely revamped to offer noticeable enhancements and new features in multiplayer mode. The fun of StarCraft II is not limited to those who played the first StarCraft, however. Even if you were a toddler when the first game came out, you'll be able to choose your faction and jump right into the fray.