At a recent press event, Starcraft II lead designer Dustin Browder told Shacknews about some of the game's single player missions.

"We've got a mission right now where every five minutes, lava rises and kills everything on the ground. Everything dies. You've got to get to the high ground or die."

Reminds me of the mission in Halo Wars where defensive lasers sweep the deck of the ship and kill your units unless you garrison them inside.

"We've got a mission right now where infested Terrans are attacking at night, but they're hiding in the ground by day, so you need to just hold out all night long like you're in I Am Legend. Like, "I've got to live!" and then day, "Get 'em! Kill 'em while they sleep!" And you run out and you burn everything as fast as you can, and then when darkness starts coming you have to get back and hide out."