No time to study chess opening theory? Secrets of Opening Surprises (SOS) consists of highly playable, unusual opening ideas. Because an SOS is such an early deviation from the regular lines in mainstream openings (usually before move six), the probability of you being able to bring the variation actually on the board is very high. If you are tired of main lines, if you are looking for simple but effective weapons to perplex your opponent, then you will feel very much at home in the world of SOS.