It's a 3v3 map and players must battle each other to reach the resource goal first, all the while balancing unit production and avoiding lava floods.
Here's the official Blizzard endorsed description: "Featuring timed lava surges and collectable mineral caches, Burning Tide is a 3v3 map that combines several thematic elements from the epic single-player campaign mission "The Devil's Playground."
"Like the campaign mission, the goal of this game is greed, and the first team to reach the specified resource total wins!"
"Players hoping to achieve victory on this map will need to work together, carefully managing their team's unit production and safeguarding their vulnerable workers as they defend against enemy forces." StarCraft II: Wings of Liberty has now sold over 3 million copies around the globe, an amazing achievement for a PC only release.