As NUFC says it is a free ball, our we say foul snooker. You(or your opponent) pot the cue ball is a foul. If your opponent(or you) can't hit the whole ball directly(any balls), then it is a free ball. If you have a free ball chance, you can press the 'free ball' button in the left upper corner and you can choose any colour of balls (including red). Of course, you can pass your turn to your opponent! If you didn't choose any, you must hit red, or it is known as a foul. REMEMBER! The points of the coloured balls are depending on what are you have to pot. For example, if you are have to pot red originally, if you nominate to pot blue ball, the point is 1. You can pot colored balls (except red) to continue your break. If you have to pot the last green ball, if you nominate to pot pink, the point is 3(point of green ball is 3). Then you must pot green to continue your break! Good luck in your games. Hope that I can help you.