Do you plan to allow for spin to be added to the cueball? In some ways I prefer the gameplay simplicity without it, but I suppose it does allow some cool trickshots.
The aim was always to write a game which was simple but effective, but there is some spin ( english ) already available. Hold down E and move the mouse to choose where on the cue ball the ball will strike. It's probably not advanced enough for anything resembling trickshots, but it's good enough to get position on the next ball.