'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:
  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