While Waterman's 1888 patented Reversi returned to prominence in the 1970'svia Othello, here is my estimation of Mollett's Game of Annexation - first published in 1870, using the same standard revisions.
 
Black and White alternate putting disks on vacant squares from an initial opening position. Each disk must be placed so that it sandwiches one or more enemy disks between itself and another friendly disk, with no empty squares intervening. The sandwiched enemy disks are flipped, changing colour. If one player can't move, he must pass his turn.
The game ends when neither side can move, usually when the whole board is filled. The winner is the player with the most pieces of his colour.