OnMouseDown

Spin Off: OnTouch

This script sends OnMouseDown messages based on taps, so you can use OnMouseDown callbacks. Attach the script to the camera that is rendering the clickable (tappable) objects. Add a layer argument to the Raycast call if you need to avoid unnecessary intersections. A similar script can be implemented for OnMouseUp (an exercise for the reader). This is only for 3D objects with colliders (e.g. this is used for the 3D menus in HyperBowl), not for GUIText and GUITexture.