In the downloadable mission, which will be released in two weeks, you battle for control of a massive cave, complete with a haunting pirate ship. Once you conquer the lair, it forever belongs to your character.

You can start a band of pirates. You can plunder. And you can decorate your captain's chamber with furniture.

Cheng also hinted at further content on the way.

"We're going to keep on releasing demos every three to four weeks as long as people keep playing," Cheng said. "We've got six or seven in the queue—one is a huge and epic dungeon."

The two downloadable missions for Oblivion are two of the top downloads on Xbox Live® Marketplace. The only thing that will change, Cheng said, is the cost. "We're really trying some different things on the pricing."

Though Bethesda is committed to downloadable content Cheng said that it will not affect expansion packs, which he didn't give a launch date for.