Comments/Ratings for a Single Item

Well I looked for the error in white's fourth move, and couldn't see it. Nothing threatens, and therefore nothing promotes, any piece on the ranks 1-2 or the c3 Knight. That leaves the B6 and g3 Bishops threatened once each, and the e4 Pawn threatened twice, so each of those three is promoted. If I have missed anything please say what it is.

I have considered the options that you suggest. Option 1 has the problem of keeping track of which Pawns have and have not promoted. Option 2 puzzles me slightly: the e4 Pawn promotes nothing until it is itself promoted. Option 3 would raise the question of which player decides which piece gets promoted.

One modification that occurs to me is that a piece does not promote a protected piece earlier in the sequence than itself, as capturing such a piece and being captured back would be a net loss of piece. So in the Fast Sequence a Knight would not promote a protected Pawn, and a Queen would promote only unprotected pieces. With that rule the sample game would run without promotions in the first five moves.

To explain my idea further :

1. Pawns are not promoted at all by the Nietzsche rule. However, when they reach the 8th rank, they are promoted as usual, and only then enter the promotion sequence.

2. After (1.e4 e5 2.Nf3 Nf6), the e5 pawn is attacked once, and not defended, so it is promoted to a Knight (assuming suggestion 1 is not in effect. Consider this : (1.e4 e5 2.Nf3 Nc6) the pawn doesn't promote, because it is now attacked once and defended once. If the game was to continue (3.d4 Nf6) the pawn at e5 promotes, because it's attacked twice and defended once.

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The only objection I have about this mutator is its clarity. It appears to be difficult to see more than one move ahead. If both suggestions above are taken into account, it will make things a little easier.

I had to think carefully about this, and in particular deal with each
sequence in turn. A general point is that this page does not refer to any
kind of counterpart, so I see no relevance in a piece having or not having
one in some other context.
	The slow sequence is taken directly from Alternate Promotion Chess (see
introduction) which requires alternation between FIDE and non-FIDE pieces.
Given the closeness in power between the Knight and Bishop any non-FIDE
piece is likely to have imperfections of the kind that you mention. Out of
couriosity, how big does a board have to get for the Bishop to overtake the
Prince in power?
	The Knighted sequence is an extension of the slow sequence and therefore
inherits the Prince from it.
	With the Courier-inclusive you are on better ground as alternation breaks
down altogether. Also, I do not use the Prince in Courier Kamil, even
though it is in the original Courier. The only snag is that it would no
longer true that 'As well as CK and FIDE arrays it can be used with the
Courier array itself', unless a special rule were applied to the Prince
in that.