In this note we describe a simultaneous version of the classical game Go or S-Go for short. This means that players move simultaneously without knowledge of the other player's move. In particular the classical Komi rule is removed, as well as the Ko rule. S-Go is a not quite perfect information game, because the other player's move is not known on the given turn. To resolve the natural issues that can occur with simultaneity we use ideas inspired by quantum mechanics, but instead of a dice roll there is a certain deterministic `quantum state' reduction, in turn inspired by ideas of the physicist Roger Penrose. In particular state evolution is deterministic. A theoretical connection of S-Go with Go is also given via a theorem.