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