At first I thought what they meant by not be constrained to an 8x8 grid was that you could basically send pieces off the map to out of bound coordinates, which

At first I thought what they meant by not be constrained to an 8x8 grid was that you could basically send pieces off the map to out of bound coordinates, which would be an interesting variant. The chessboard would be an infinite size grid, you just have the start positions set to a particular 8x8 region. This has interesting implications when you start to consider pieces that could move all the way to infinity, such as a rook. Would a rook that is the first to move to infinity be able to consume any other piece that also goes out to infinity by moving horizontally or vertically? So do you have to specify that you are only moving a piece within a certain amount of squares from infinity, to not be placed in a vulnerable spot?