Initially, it struck me that a number of other pieces could be placed where the Man is placed in the array for the game described on the previous page. Any piece of limited mobility, such as a Fers, a Wazir, a Walker (Wazir-mover, Fers-capturer), a Count, or a Duke would work in about the same way. Or a somewhat more powerful piece, such as a Princess, or even a much more powerful piece, such as the Gryffin, could be used.
For something that would add a more significant novelty to the game, as the Checkers, Tigers, and Cannon do, I have now thought of a suitable piece, which I will call the Flag.
A Flag can be captured like any ordinary piece, but it cannot capture or be moved on its own.
The King, however, on any move where it is not in check, can exchange places with the Flag; this is a normal move, and can happen as many times as desired during the course of the game. Note that the Flag also must not be en prise when this move is made, as the King cannot move into check.
When the King exchanges places with the Flag for the first time, if one or both of the Rooks has not been moved, it regains the power of Castling. Thus, a possible sequence of moves, with the rest of the back rank cleared, would be for the King to Castle Kingside, then exchange places with the Flag, and then, from the Flag's starting square, Castle to the Queenside, and then exchange places with the Flag to return to the snug safety of a Kinside Castled position.
Incidentally, note that the increased defensive resources offered with this variant, which I will call Flag Chess, might be nicely balanced by the increased resources available to the player who has obtained an advantage, through re-entering captured pieces, in Antimatter Universe Chess, making Antimatter Universe Flag Chess a variant of particular interest.
Here, then, is an image of the initial array for the chess of the future, Antimatter Universe Flag Chess:
In addition to balancing the offence and the defence, the branching factor for each move for that variant would be increased, helping to make the game harder for computers. In addition to the large number of possibilities for drops, the ability of Checkers to carry out multiple jumps also provides an increase in the number of possible moves. Also, the positional factor involved with Tiger captures, and the decision to pursue a victory smaller than checkmate, will present challenges to computer players.