Hexade
HexadeHexade was really simple because the ingredients were bound to come together at some point. Like Havannah it has three winning structures. Like Pente it allows the custodian capture of 'pairs' of opponent's stones. The 'invention' boiled down to spotting the 'three sixes', six in a row, six in a compact triangle and six around one cell.
Unlike Pente, capture is only a means to an end, not an end in itself. A player only wins by completing a 'perfect six', a winning structure that outlasts the opponent's next move.
Unlike Havannah, the three winning conditions are defined by shape. That makes Hexade, however deep, a tactical game. Everybody can start a game without being in the dark about what's going on.