An update to Angry Birds has been released adding a new underground episode, Mine and Dine, with 15 new levels. In this latest episode, the bad piggies are now hiding in underground caverns with the stolen eggs; players must chase the pigs out of their hiding holes using the landscape and geology such as hanging stalactites to retrieve the eggs and gather rare collectible gems. The Mighty Eagle power up introduced in the previous version also remains available as an in-app purchase even in the underground levels to help players pass the more difficult levels. The update also makes some minor changes to some of the tougher game levels to reduce their difficulty. Angry Birds for the iPhone and iPod touch is available from the App Store for $1; Angry Birds HD for the iPad is available separately for $5. The Mighty Eagle is available as a one-time in-app purchase for $1.