Minima

Minima is small board variant that draws most inspiration from the popular Chess variants Ultima and Maxima. 

While drawing its name and some of its elements from the latter, it is principally an attempt to modernise the original game of Ultima, and address some of its flaws (piece imbalance, spare pieces, clunky pawns, no promotion, overly defensive gameplay, with slow but difficult to capture king, and no alternative game objectives), creating a sleeker, more compact game, with no sacrifice to its complexity.

Setup

It is played on a 6x6 cylindrical board, with 6 pawns, a king and 5 officer pieces.

Default starting array, from A1 to F1, is Coordinator-King-Chameleon-Long Leaper-Displacer-Immobiliser (see pieces).

Pieces

Pawns are similar to pincer pawns of Ultima, but with different movement. They may move up to 2 squares in any sideways or forward direction, but never backwards. They capture by custodial capture as in Ultima, by flanking an adjacent piece. These pawns however are not restricted in allignment, in other words they can capture an orthogonally positioned piece with diagonal or orthogonal movement and vice versa. Pawns are promoted on final rank.

The King moves and captures like a knight, and is central to the games 2 objectives. If he is captured you lose, but he can win the game by reaching an opposition "corner" (there are being of course no true corners on a cylindrical board) square (the game can also be won by positioning a piece on both squares.

The 5 officers are comprised of the Displacer (FIDE Queen), and the Immobiliser, Long Leaper, Chameleon, and Coordinator from Ultima, with the Advancer (from Rococo), plus Ultima Withdrawer compound, the "Pushme-Pullyu", available as the 1st Pawn promotion.

The latter Chameleon and Coordinator get an upgrade; the Chameleon captures any piece with Queen movement, regardless of the pieces own movement type. A Chameleon may also attack another Chameleon now under exceptional circumstances; if a Chameleon is threatening a piece or has just captured a piece, the other Chameleon may capture it in that fashion.

The Coordinator may now also capture with diagonal interception with the King, also on the Kings movement, being able to fully utilise the cylindrical board for captures involving diagonal interception.

Rules

Game is won by 1) capturing opponent King, 2) stalemating opponent, 3) getting own King to one of the opposition corner squares, or positioning a piece on both squares.

Pawns promote 1st to a Pushme-Pullyu (from one of Rococo variants) and any captured friendly piece for further promotions thereafter.

Notes

When picking appropriate pieces, bearing in mind the need to keep close to the original material, in keeping with the spirit of this variant, it came down to picking between the Displacer, Pushme-Pullyu, and Long Leaper for 2 remaining slots. They're all 3 linear capturing pieces not altogether different in power, while the other 3 pieces all offer unique abilities that add something different. The most dispensable of those was probably the Chameleon, but this acts as important counterbalance to the dominant Immobiliser.

In picking between the 3 linear attackers, I preferred the more directness simplicity of the Displacer whose attack power isn't restricted by a clustered board, with the Long Leaper as 2nd choice. But any combination is playable. The 3rd can always be made available as 1st promotion piece, or even played into the game for another variant, in which I would drop it on starting rank square vacated when playing another piece. But in my opinion, with 66% piece density the board is clustered enough...

The decision to make the board cylindrical was a natural one to arrive at given the cluttered board and clear disadvantage pieces like the Long Leaper and Pincer Pawns in particular suffered from the large percentage of edge squares that exist on such a closed small board. The King too is otherwise quite unwieldy on such a board.

The coordinator was already given a 2-fold boost in passive capture and diagonal interception, but actually receives a 3rd in that the cylindrical board allows 4 diagonal intersections with the King, allowing a total of up t 6 captures in a turn.