<sup>According to its creators, StarCraft II is designed to be the "ultimate competitive real-time strategy game", building on the successes enjoyed by its predecessor, StarCraft. It features the return of the three races from the original game—Protoss, Terran, and Zerg; Blizzard states these are the only playable races in the game. StarCraft II is also designed to focus more heavily on the multiplayer aspect, when compared to the original StarCraft. The changes include overall improvement in Battle.net, a new competitive "ladder" system for ranked games and new matchmaking mechanics—designed to "match-up" players of equal skill levels. In addition, the replay function, which allows players to record and review past games, is being improved. Blizzard has also stated they have made some changes to the game that were suggested by fans.

StarCraft II continues its predecessor's use of pre-rendered cinematic cut scenes to advance the plot while also improving the quality of in-game cut scenes within the levels themselves, which are rendered on-the-fly using the same game engine as the graphics in the game proper. Blizzard states that with the new graphics engine that StarCraft II uses to render the gameplay, they "can actually create in-game cut-scenes of near-cinematic quality".

Most Protoss and Terran units, and some Zerg units, have been shown on the StarCraft II official website, and in several video demonstrations held by Blizzard.Improvements include advanced scenery allocation and more detailed space terrain, such as floating space platforms with planets and asteroids in the background. Small cliffs, extensions, and even advertising signs were also shown to have been improved and refined.
The new Terran briefing system allows the player to explore the inside of the battlecruiser Hyperion.

The single-player aspect of StarCraft II has also been altered substantially from the original game. The Terran campaign shown at BlizzCon 2007 replaced the original StarCraft briefing room with an interactive version of the battlecruiser Hyperion, with Jim Raynor, now a bitter and hard-drinking mercenary captain, as the central character. In a departure from previous Blizzard games, the campaign is non-linear, with Raynor taking jobs for money and using that money to buy additional units and upgrades. Although each playthrough will vary, the end result will remain consistent keeping the storyline linear. Vice president Rob Pardo has stressed that each campaign will function very differently.The Terran campaign, Wings of Liberty, will place players in a mercenary style campaign, as Terran rebel Jim Raynor performs missions for cash. The second release, the Zerg campaign Heart of the Swarm, will have RPG elements. The player will level up the Queen of Blades, Kerrigan, throughout the missions. In the last expansion, the Protoss campaign Legacy of the Void, the dark templar Zeratul will have to employ diplomacy between Protoss tribes to acquire units and technologies for each mission. Each campaign should span 26-30 missions.</sup>

TBA