Topware Interactive's Two Words II: Castle Defence is the first iOS game to allow players to control the action with their eyes.

The latest update for the app introduces 3D-ET technology, while uses the iPad 2's front-facing camera to follow the gamer's eye movements. According to Topware, this enables the players to "look around corners" and change the perspective of the castle defence game by moving their eyes.

The company added that the eye-tracking technology has also been available in the free Lite version of the game.

"By introducing the new Eye-tracking technology we are ahead of the competition once more and will expand this edge in the future," said Topware's CEO Dirk P. Hassinger.

"Right now we are adapting the system for platforms like PC or Mac and will also present some challenging 3D surprises within the next couple of months."