The idea of a fixed move that can be described by a notation implies a board with regular tiling. Such a tiling can have other connectivity than the usual 8-neighbor square-cell topology, e.g. hexagons or triangles. But these could have their own, completely independent system of atoms and directions, reusing the available letters for their own purposes.
I have thought about supporting hexagonal boards in the Interactive Diagram. This could be done by representing the board as a table with a column width half the piece-mage size, and give every table cell a colspan="2", in a masonic pattern. That would distort the board to a parallellogram. A numerical parameter hex=N could then specify how large a triangle to cut off at the acute corners. The board could then be displayed without border lines and transparent square shade, so that a user-supplied whole-board image with hexagons could be put up as background for the entire table. This would purely be a layout issue; the rest of the I.D. would know nothing about it. In particular, the moves of the pieces would have to be described in the normal Betza notation as if the pieces were moving on the unslanted board. E.g. a hexagonal Rook would be flbrvvssQ.
About castlings: one can of course think up any sort of crazy move, and present it as a castling option. But in orthodox Chess castling exists to fulfil a real need, rather than the desire to also have a move that relocates two pieces at once. The point is to provide a way to get your King to safety without trapping your Rook, and without having to break the Pawn shield. Sandwiching a piece between your Rook and King doesn't seem to serve a real purpose. If the piece could easily leave you could have done that before castling, and if not than it is still semi-trapped.
A more sensible novel form of castling would be where multiple piece end up at the other side of the King. E.g. when the piece next to the Rook would be a Moa ([F-W]), conventional castling is not up to the task. You would need a castling that moves the Rook to f1, and the Moa to e1, upon castling to g1 on 8x8. Of course you could argue that this is a defect of the start position, and could better be solved by choosing a setup that had a jumping piece on b1/g1.
The idea of a fixed move that can be described by a notation implies a board with regular tiling. Such a tiling can have other connectivity than the usual 8-neighbor square-cell topology, e.g. hexagons or triangles. But these could have their own, completely independent system of atoms and directions, reusing the available letters for their own purposes.
I have thought about supporting hexagonal boards in the Interactive Diagram. This could be done by representing the board as a table with a column width half the piece-mage size, and give every table cell a colspan="2", in a masonic pattern. That would distort the board to a parallellogram. A numerical parameter hex=N could then specify how large a triangle to cut off at the acute corners. The board could then be displayed without border lines and transparent square shade, so that a user-supplied whole-board image with hexagons could be put up as background for the entire table. This would purely be a layout issue; the rest of the I.D. would know nothing about it. In particular, the moves of the pieces would have to be described in the normal Betza notation as if the pieces were moving on the unslanted board. E.g. a hexagonal Rook would be flbrvvssQ.
About castlings: one can of course think up any sort of crazy move, and present it as a castling option. But in orthodox Chess castling exists to fulfil a real need, rather than the desire to also have a move that relocates two pieces at once. The point is to provide a way to get your King to safety without trapping your Rook, and without having to break the Pawn shield. Sandwiching a piece between your Rook and King doesn't seem to serve a real purpose. If the piece could easily leave you could have done that before castling, and if not than it is still semi-trapped.
A more sensible novel form of castling would be where multiple piece end up at the other side of the King. E.g. when the piece next to the Rook would be a Moa ([F-W]), conventional castling is not up to the task. You would need a castling that moves the Rook to f1, and the Moa to e1, upon castling to g1 on 8x8. Of course you could argue that this is a defect of the start position, and could better be solved by choosing a setup that had a jumping piece on b1/g1.