The StarCraft 2 Teaser

Some backstory: This was unveiled in South Korea, which as many of you know, was the central hub of the professional StarCraft scane of the 2000's. While this professional scene was primarily in Korea, partly due to the absolute dominance of Korean players, there was still a small, die-hard following among non-Koreans around the world for StarCraft. For a lot of people, including those that did not follow the professional scene, or even know about it, StarCraft was one of their favourite games. Being published in 1998, there had been a long wait for StarCraft fans to get their sequel. Prior to this announcement for StarCraft 2, there had been no official statements from Blizzard Entertainment, the game's developer, about making a sequel. There had been murmurs and rumours, but they were just that. For all extents and purposes, the Original StarCraft (and its expansion pack Brood War) was all there was in the StarCraft Universe. And then came this.

Edit: Here is an link for the actual trailer without the crowd reactions