# 'Pure' Rules of Ultima (also known as 'Baroque Chess')

We wish to highlight a variant of the board game Ultima, originally invented by Robert Abbott. Abbott recommends this page for the rules.

The rules I learned from Roger Sewell in 1974, which I term the 'pure' rules of Ultima (because they seem to me simpler and more logical, not because they predate Abbott's!), do not seem to be prominent anywhere on the internet. The aim of this webpage is to propagate the 'pure' rules, which Roger and I both believe make a good game.

| Differences between the 'pure' rules and the rules on chessvariants.org | The pure rules in full |

### The differences

The differences between the 'pure' rules and the rules on the internet chessvariants.org concern the chameleon and the immobilizer.

Can a chameleon simultaneously capture leapers, withdrawers and pawns? According to wikipedia a chameleon can simultaneously take 7 pieces (two leapers, 3 pawns, one coordinator, and one withdrawer). But in the pure rules, this move, while legal, would take ONLY THE LEAPERS: it is illogical to allow the chameleon to take the pawns since to take pawns chameleons should move as pawns do, which means not leaping over anything; to take the withdrawer, the chameleon should withdraw from it in the style of a withdrawer, which means not leaping over anything; and likewise for the coordinator. If the two leapers were not on the board then the same chameleon move WOULD simultaneously capture the three pawns, the withdrawer, and the coordinator, because that move would match the description of how each respective piece would capture.

Immobilizers: The pure rule on immobilisation is:

A friendly piece X is immobilised if either (or both) of the following apply:

a) It is an immobiliser and adjacent to an enemy chameleon.

b) It is adjacent to an enemy immobiliser next to which is no friendly chameleon or immobiliser other than X.

So, if for example a W chameleon moves alongside a B immobilizer, all adjacent ordinary W pieces that were immobilized are free to go again, except the W chameleon.

If there are 2 W chameleon next to a B immobilizer then either chameleon is free to move away.

In contrast, the rules on the internet treat the above situations differently; they also permit a move of "removing one of one's own imbolized pieces from the board", a 'move' that does not exist in the 'pure' rules.

| Differences between the 'pure' rules and the rules on chessvariants.org | The pure rules in full |
 Starting position of Ultima

### The pure rules in full

1. There is no choice of starting position in the pure rules. The starting position, shown here, is the mirror image of the position shown on wikipedia (not that it much matters). The immobilizers are diagonally opposite each other, and the king is close to his immobilizer. Mnemonic: King and immobilizer are on your right as you look at the board; so white's positions look like normal chess; black's look like chess except for the reversal of his queen and king.
2. The names of the pieces and rules for movement are as follows:
• The King moves and captures like a standard chess King. The objective of the game is to checkmate the opposing king.
Clarification:
Aim of the game is to checkmate the opposing king, not "to capture the opposing king" - e.g. an immobiliser and king can force checkmate, but cannot force capture of the king (because at the moment of check, the checked king would have no legal move, thus there would be a stalemate before the winner had the chance to make the 'capture').
• The pawns move like standard chess Rooks. A pawn captures any opposing piece horizontally or vertically between the square to which the pawn moved and a friendly piece. Pawns never capture diagonally, only horizontally or vertically.
• The remaining pieces all move like standard chess queens, but have unique methods of capture. None of them captures like a standard chess queen. None of them may move onto an occupied square.
• In all the following rules, two squares are `adjacent' if they are adjacent vertically, horizontally, or diagonally.
• The Withdrawer, represented by the Queen, captures by moving directly away from an adjacent piece along the straight line joining the starting position of the Withdrawer and the position of the piece being taken.
• The long-leaper, represented by the Knight, captures by jumping over an opposing piece in a straight line. A long-leaper may make multiple captures in the same line as long as there are one or more intervening empty squares. A Long Leaper may never jump over a friendly piece, jump over adjacent pieces, or move to an occupied square.
• The Coordinator, represented by the unmarked Rook, captures whatever opposing piece is on its file and the King's rank, or the King's file and its rank, or both, after the Coordinator has moved.
• The Immobilizer, represented by the inverted Rook, does not capture anything, but immobilizes all adjacent enemy pieces. The effect of an immobilizer may be neutralized by the enemy immobilizer or enemy chameleons, as described by the following complete rule:
A friendly piece X is immobilised if either (or both) of the following apply:
a) It is an immobiliser and adjacent to an enemy chameleon.
b) It is adjacent to an enemy immobiliser next to which is no friendly chameleon or immobiliser other than X.
• The Chameleon, represented by the Bishop, captures any piece by moving as a piece of the type captured would have moved to capture. For example, in order for a Chameleon to capture an enemy King, it must begin its turn adjacent to it, and step into its square, because the King is the only piece on the board that steps one square at a time, and captures by 'replacement' - stepping into the enemy's square to capture it. Also Chameleons immobilize enemy Immobilizers to which they are adjacent. as described in the previous rule. Chameleons cannot capture Chameleons.
3. Immobilized pieces may not 'commit suicide'.
4. If a player cannot move without moving into check, the game is a draw (stalemate).
5. If 50 moves by each player elapse without a piece being taken, the game is a draw.
6. If the same position occurs three times the game is a draw.

| Differences between the 'pure' rules and the rules on chessvariants.org | The pure rules in full |

Further notes:
The following two minimal-piece endgames are fun to explore:

1. King and immobiliser versus king alone; In this particular endgame, the friendly king and immobiliser force the enemy king to move up to the immobiliser at a time when the friendly king can then sidle up to him, putting him in check. So he's checkmated - because he cannot move out of check - but hasn't been (and never will be) taken.
2. King, coordinator, and 2 pawns versus king alone.
3. Both are forced wins for the team with more pieces, but decidedly non-trivial to achieve.

David MacKay January 2006