Gauging interest: Progressive (Italian) Chess — a multi-move-per-turn variant

[Arthur-Freedom]

Hi, and thanks for pychess — it's the best home for chess variants on the web.

I'd like to gauge whether Progressive Chess (specifically Italian Progressive
Chess) could ever be of interest here, or whether it's firmly out of scope.

What it is: players make progressively longer sequences of moves — White plays
1 move, Black plays 2, White plays 3, Black plays 4, and so on. A check may only
be given on the LAST move of a sequence, and you may not expose your own king to
check during your turn. It's a small but long-standing variant (there's a
dedicated program by Vito Janko, and a recent book "Learn and Master Progressive
Chess" by Matej Guid).

The honest catch: I know pychess relies on Fairy-Stockfish for move
generation/validation, and progressive chess's "N moves per turn" structure
isn't something Fairy-Stockfish models — so I realize this likely falls outside
what pychess can support. I'm not asking anyone to take on that work.

Why I'm posting anyway: I've built a working implementation — a custom engine for
Italian progressive chess (multi-move turns, check-only-on-last-move, mate
detection) plus ~290 verified mate puzzles (including the 240 from Guid's book).
So the rules/engine side is already solved on my end.

My questions:

1. Is there any appetite for a multi-move-per-turn variant on pychess, or is
   "must be Fairy-Stockfish-supported" a hard line?
2. If it's out of scope (totally understandable!), would you be open to
   linking/mentioning a dedicated progressive-chess site for players who look
   for it here?

Either way — thanks for the great project!

[gbtami]

Yes, "must be Fairy-Stockfish-supported" is a hard requirement, unless our code base will be hard to maintain.
There are very few exceptions like fogofwar and jieqi which needed some minor python/typescript glue code to work, but basically they both can use Fairy-Stockfish at lest for move generation.

You can fork pychess and adjust its code to use your engine, but the whole site is based on the assumption of one move per side in every turn principle, so it will not trivial.