Hearthstone: Heroes of Warcraft
Hearthstone is a digital collectible card game developed by Blizzard Entertainment, the same people behind World of Warcraft. All of the cards you will use are from the Warcraft universe, such as Ragnaros and Illidan.
A lot of people agree that Hearthstone is one of the more successful digital CCGs currently available because of how easy it is for people to learn, and how short the games are (around 10 minutes). Now is the right time to jump in as they have recently released the Goblin vs Gnomes expansion, which will upset the currently existing meta decks (the ones with the highest success of winning).
At the moment it is free on iPad 2 and above, but does include in-app purchases. They have announced via the Battle.net Blog, that Hearthstone will be coming to Android tablets before the end of this year, followed by iOS and Android phones early next year.
Why is it great to play while taking care of your morning business? The games are only around 10 minutes long, and it is easy to pick up and play.