Interaction is the key to an application. It brings graphics to live, creates a user experience, and enables a seamless immersion space. Interaction has different forms: touch, voice, gestures, mouse or even textual input. The problem is to select an adequate way for the application.
Sound plays an important role in interaction (see Sound aesthetic). It transports emotion, provides feedback, or 'visualizes' values.
Boundaries are inherent in computer games and restrict us to a place in front of the computer communicating using codes. At this point the concept of mixed reality starts by breaking or blurring them, "freeing the player". The point of interaction is moving away from devices towards a more natural user interface. Players actions are no longer indirect and mediated by devices: a jump will become a jump, run is running. The abstract buttons/arrows are replaced by direct actions of the user. Real actions and gestures are translated into virtual ones with a nearly one-to-one mapping.
Airkanoid is a mixed reality remake of the classical Arkanoid from Taito. The new mixed reality interface allows more natural interaction beyond mouse, keyboard and joystick. Real bats are tracked and the bodily actions are translated into game events. A tight coupling between the player and the game is created.