Downloaded your game (rated it), just a small tip, make the timer react when you press the button on the down event, it is now only working on the up event which is not your reaction time but the reaction time + the button down and up time of your finger.
And a bit more graphics can't hurt as well
Was this your first project? Working on any other projects? If you want to venture into the world of OpenGL 2d game development, I have made some tutorials on OpenGL ES 2.0 2D game development on my blog at androidblog.reindustries.com
