Here are the controls (the game has no tutorial) :

You control the camera like the unity editor camera (e.g. you move with the arrow keys or wasd (w/up = forward, a/left = left, d/right = right, s/down = backwards) you rotate the camera by holding the right mouse button and then moving the mouse. You can pull the camera up, down, to the right and to the left by holding down the middle mouse button. You aim the shot by holding down the left mouse button and then pulling in the opposite direction in which you want the ball to fly