Today, Blizzard replaced its demo for StarCraft 2: Wings of Liberty from its website, replacing it with a new trial based on a similar platform as its recent changes to the World of Warcraft trial.

StarCraft 2: Starter Edition includes the game's first four missions, whereas the original demo only featured three. The Starter Edition also gives players access to the first two challenges in the game.

According to the announcement post on Blizzard's official site, the missions included in the demo are "Mar Sara 1-3 and the choice to embark on Tychus’s first mission or Dr. Hansen’s first mission."

Like the original demo, players are restricted to the Terran race in skirmish play against the AI. For the first time, players can test the waters online against other players in a rotating set of custom maps.

The current set of maps include Xel’Naga Caverns, Shattered Temple, Discord IV, and High Orbit.

Unlike the original demo, however, the "Starter Edition" of StarCraft 2 requires a Battle.net account to access. The Starter Edition also requires constant connection to the internet.

Blizzard notes: "Any campaign progress and achievements you earn while playing StarCraft II: Starter Edition are automatically saved to your Battle.net account, and will carry over should you ever upgrade from the Starter Edition to the full version of StarCraft 2: Wings of Liberty."

The original demo is still available for download from Shacknews.