There seems to be a secret level in Starcraft 2 after-all. I kind of figured this would be the case since I beat the game with about 25 out of 26 missions completed. Here is what Cheat Code central states:
“Piercing The Shroud” secret mission
In the “Media Blitz” mission, where you control the Odin in the city, go to the far bottom-right corner of the map. Destroy the red civilian building on the little floating platform. There is a pathway to the building from the small enemy expansion base that is just north of the player’s starting position. Once the building is destroyed, “secret documents” will be revealed. Pick the “secret documents” up with any ground unit, and then complete the mission as normal. The “Piercing The Shroud” secret mission will now be accessible through the Star Map. Note: You cannot play the secret mission after going to Char, as you have to go to another planet. Thus, you must go to the load menu and load a game from before Char to play the mission.
Sidenote: It seems that StarCraft also pokes at the Batman moves with the cheat code “whysoserious“. This cheat gives the player 5 billion credits in the single player campaign. In addition, it pokes fun at the more dots wow video with the cheat code “moredotsmoredots” in which units do not cost resources.
Here are some videos: