The expansion pack to the award winning first-person puzzle game is exclusive to Xbox 360 and arrives October 22 on Xbox Live Arcade at 5 AM EST.

"In addition to the original award winning first-person puzzle experience, Aperture Science is proud to provide 14 new challenge maps exclusive to Xbox Live Arcade," Microsoft said in a statement today. "Six advanced maps will also be provided to help guide you along the way."

Given the inclusion of the entire first game, not to mention the clever gameplay puzzles, the expansion looks to be a bargain at US$15 (1200 Microsoft Points).

The first Portal was included in last year's Orange Box compilation and is often considered the best of the five bundled games.