This game belongs to a series of 4 games by Scandecor, which come in a square plastic board (Play Cavalry, Play Balance, Play Ecology and Play Numeric).
The board has 12x12 spaces and each of them is made as a 3d-hole, where you can place a tile looking to one player or to the other by tip over the tile.
One player plays with the 48 water tiles and the other takes the 48 land tiles. Each tile can be moved 1 space in advance. Captures (accomplished sideways) can be done when a tile can move to an empty space, which has an opponents tile directly adjacent to it. Since the tiles are facing in 2 directions, the rules use the term "overshadowed" for such tiles. The capture is done by tipping over the captured piece and if there are additional tiles directly behind the captured piece, you can tip over these tiles also.
The game ends, when all positions are blocked, that is when no reasonable moves can be made by neither player. You simply count the tiles then to see, if the water or land player has won the game.