Are there special equipment to fix a camera in a top down view?
(This is an alternative to mounting a camera above a game board.)
If it proves difficult to mount and operate a camera above the board, consider using a mirror as an alternative. The camera can be placed on a normal tripod, and a mirror can be mounted above the board on a 45-degree angle. The camera then shoots the image in the mirror.
The image will need to be flipped vertically in post-production to avoid showing a mirror image of the board.