H. G. Muller wrote on Fri, Oct 13, 2017 06:59 AM UTC:
O = castling (chosen because of O-O / O-O-O in SAN), s = sideways, 2 = piece makes exactly two steps, i = virgin piece only.
That the Rook, as virgin corner piece, ends up next to the King on the other of the latter, is implied by the O atom. On 10-wide boards it is more customary to have O3 castling. The only description of this variant that Google came up with (chess10x10.com) just gives the setup, says that Archers are non-royal Kings, and that otherwise FIDE rules apply. I interpreted the later as O2 castling, although when you think of Chess960 it would be possible to argue that it should actually mean O3 castling on 10-wide boards. I also interpreted this as that there is no initial triple push on the Pawns.
I am not even 100% sure of the name 'Archer'. The description I found only says 'non-royal King', but I vaguely remember having seen a description long time ago where they were called Archers. (Or Centurions?) I added the variant to Fairy-Max at the time I implemented support in the latter for boards with other than 8 ranks, as a simple example of a 10x10 variant. The comment in the game definition there refers to the new pieces as 'Archers', and uses the letter A as ID for them. I must have gotten that from somewehere...
O = castling (chosen because of O-O / O-O-O in SAN), s = sideways, 2 = piece makes exactly two steps, i = virgin piece only.
That the Rook, as virgin corner piece, ends up next to the King on the other of the latter, is implied by the O atom. On 10-wide boards it is more customary to have O3 castling. The only description of this variant that Google came up with (chess10x10.com) just gives the setup, says that Archers are non-royal Kings, and that otherwise FIDE rules apply. I interpreted the later as O2 castling, although when you think of Chess960 it would be possible to argue that it should actually mean O3 castling on 10-wide boards. I also interpreted this as that there is no initial triple push on the Pawns.
I am not even 100% sure of the name 'Archer'. The description I found only says 'non-royal King', but I vaguely remember having seen a description long time ago where they were called Archers. (Or Centurions?) I added the variant to Fairy-Max at the time I implemented support in the latter for boards with other than 8 ranks, as a simple example of a 10x10 variant. The comment in the game definition there refers to the new pieces as 'Archers', and uses the letter A as ID for them. I must have gotten that from somewehere...