Glimmer Chess

Rules

This variant is based on Twilight Chess, with the following rule amendments:

1. The off-board zone is termed the Glimmer-zone and may hold a maximum of 4 pieces (includes Pawns but not the King).
2. Pawns may be dropped on any vacant square in their own half of the board except for the first rank: in other words the drop-zone for a Pawn consists of vacant squares in ranks 2,3,and 4 for white; or ranks 5,6, and 7 for black.
3. The drop-zone for Knights, Bishops, Rooks and Queens consists of any vacant square behind and adjacent to a friendly Pawn or King.
4. Each player has an initial Glimmer-move with which they may place up to 4 pieces in the Glimmer-zone and relocate their King to one of the vacated squares. A player may choose to pass this initial move.
5. Any Pawn on its own second rank has the option of a double-move.
6. Castling is allowed as is en-passant capture.

Notes

1. Twilight chess mentions no limits as to the number of pieces that may occupy the off-board zone. My instinct (which may well be wrong) is that this may lead to drawish games with both sides avoiding engagement by placing their pieces off-board.
2. and
3. Twilight chess allowed pieces to be dropped almost anywhere, one consequence of which would be the reduction in importance of Pawn structure. To redress this I have restricted the drop-zone as outlined above.
4. The introduction of the Glimmer-move should make it more difficulr for software to play well.
5. This rule avoids having to remember which Pawns have moved.
6. Mentioned for clarity.

---