I have the game concept worked out and I'm going over the list of pieces
and writing a ZRF.
Pieces will have value classes from 1 for pawns, 2 for minor pieces, up to
8 for an Amazon-rider (!). If you don't have a piece in your pocket you
may remove one of your pieces (not your king) from the board and put it
'in your pocket'. This piece is is immediately demoted one value class
(but pawns are not demoted)--except when the piece is removed from the
eight rank: in that case the piece is immediately promoted one value class
(but a class 8 piece remains class 8). You may choose any piece of the
appropriate value class when you put the piece in your pocket.
If you have a piece in your pocket, you may drop it on the board. A class
1 piece (pawn) may drop anywhere on the board, a class 2 piece may drop on
the first to seventh ranks, a class 3 piece on the first to sixth ranks,
and up to a class 8 piece can only drop on the fisrt rank.
Pocketing and dropping each count as moves.
Promotion is done only by pocketing on the enemy eighth rank, so it is
legal to pocket a pawn, drop it on the eight rank, repocket it and promote
to a minor piece. But this will take four moves to get the minor piece on
the board. Pocketing and dropping closer to the eight rank for promotion
won't be used for non-pawns as you demote one class for the first
pocketing and the promotion takes you back to where you started-- though
this could be a viable way to reconfigure your army.
A pawn dropped on the first rank may not take a double step, a pawn
dropped on the second rank or moved up from the first rank may. Castling
may not be done with a dropped Rook.
Your may keep a piece in your pocket as long as you wish, but you choose
the new piece when the piece goes in to the pocket.
Strategy and tactics will focus on breaking through to the enemy back rank
to use it for promotions.
I would like to hear suggestions for the pieces in each value class.